I'm not 100% sure how to explain this. I'm using image builder for 19.07.7.
When I make the image, I can see two of the packages I want being downloaded, configured and enabled. The packages are vnstat and a zabbix agent.
I then install the firmware on the device and poof, those two packages are gone and maybe others I've not noticed yet. I can see the firmware is the correct version so what could be happening?
I can install the packages manually once the new firmware is running too.
Are they included in the manifest list (in the build folder) after the build?
A little long shot you can try since 19.07.7 image builder had a driver fault for Linksys.
You could try to build with the 19.07-snapshot instead to see if it changes the situation?
I'm building for a gl.inet device.
I use a files/ directory where I put my pre-configured config files, for example, vnstat.
I have vnstat in the list of packages for my build. I see vnstat getting downloaded, installed and enabled.
Once I boot the fw, there is no vnstat package installed and my config files were overwritten.
There are quite a few people on this forum who love to help others, however, without additional information it's a guessing game rather than pointing out the problem.
Assume others would want to help you so much, they'll try to reproduce your problem -- go step by step how you get from a pristine OS/VM/system to the point where you build the flawed image.
The more information you provide, the better quality replies you may get.
I've tried a build with image builder for 19.07.7 for your device and this command
make image PROFILE="gl-mt300n-v2" PACKAGES="bash bc curl vnstat zabbix-agentd"
and I see the packages I added with that line in the openwrt-19.07.7-ramips-mt76x8-device-gl-mt300n-v2.manifest
base-files - 204.2-r11306-c4a6851c72
bash - 5.0-4
bc - 1.06.95-1
busybox - 1.30.1-6
ca-bundle - 20200601-1
curl - 7.66.0-3
dnsmasq - 2.80-16.3
dropbear - 2019.78-2
firewall - 2019-11-22-8174814a-3
fstools - 2020-05-12-84269037-1
fwtool - 2
getrandom - 2019-06-16-4df34a4d-4
hostapd-common - 2019-08-08-ca8c2bd2-7
ip6tables - 1.8.3-1
iptables - 1.8.3-1
iw-full - 5.0.1-1
jshn - 2020-05-25-66195aee-1
jsonfilter - 2018-02-04-c7e938d6-1
kernel - 4.14.221-1-d92769dc5268e102503ae83fe968a56c
kmod-cfg80211 - 4.14.221+4.19.161-1-1
kmod-gpio-button-hotplug - 4.14.221-3
kmod-ip6tables - 4.14.221-1
kmod-ipt-conntrack - 4.14.221-1
kmod-ipt-core - 4.14.221-1
kmod-ipt-nat - 4.14.221-1
kmod-ipt-offload - 4.14.221-1
kmod-leds-gpio - 4.14.221-1
kmod-lib-crc-ccitt - 4.14.221-1
kmod-mac80211 - 4.14.221+4.19.161-1-1
kmod-mt76-core - 4.14.221+2021-02-15-5c768dec-1
kmod-mt7603 - 4.14.221+2021-02-15-5c768dec-1
kmod-nf-conntrack - 4.14.221-1
kmod-nf-conntrack6 - 4.14.221-1
kmod-nf-flow - 4.14.221-1
kmod-nf-ipt - 4.14.221-1
kmod-nf-ipt6 - 4.14.221-1
kmod-nf-nat - 4.14.221-1
kmod-nf-reject - 4.14.221-1
kmod-nf-reject6 - 4.14.221-1
kmod-nls-base - 4.14.221-1
kmod-ppp - 4.14.221-1
kmod-pppoe - 4.14.221-1
kmod-pppox - 4.14.221-1
kmod-slhc - 4.14.221-1
kmod-usb-core - 4.14.221-1
kmod-usb-ehci - 4.14.221-1
kmod-usb-ohci - 4.14.221-1
kmod-usb2 - 4.14.221-1
libblobmsg-json - 2020-05-25-66195aee-1
libc - 1.1.24-2
libcurl4 - 7.66.0-3
libgcc1 - 7.5.0-2
libip4tc2 - 1.8.3-1
libip6tc2 - 1.8.3-1
libjson-c2 - 0.12.1-3.1
libjson-script - 2020-05-25-66195aee-1
libmbedtls12 - 2.16.10-1
libncurses6 - 6.1-5
libnl-tiny - 0.1-5
libpcre - 8.43-1
libpthread - 1.1.24-2
libreadline8 - 8.0-1
libubox20191228 - 2020-05-25-66195aee-1
libubus20191227 - 2019-12-27-041c9d1c-1
libuci20130104 - 2019-09-01-415f9e48-4
libuclient20160123 - 2020-06-17-51e16ebf-1
libxtables12 - 1.8.3-1
logd - 2019-06-16-4df34a4d-4
mtd - 24
netifd - 2021-01-09-753c351b-1
odhcp6c - 2021-01-09-64e1b4e7-16
odhcpd-ipv6only - 2020-05-03-49e4949c-3
openwrt-keyring - 2021-02-20-49283916-2
opkg - 2021-01-31-c5dccea9-1
ppp - 2.4.7.git-2019-05-25-3
ppp-mod-pppoe - 2.4.7.git-2019-05-25-3
procd - 2020-03-07-09b9bd82-1
swconfig - 12
terminfo - 6.1-5
ubox - 2019-06-16-4df34a4d-4
ubus - 2019-12-27-041c9d1c-1
ubusd - 2019-12-27-041c9d1c-1
uci - 2019-09-01-415f9e48-4
uclient-fetch - 2020-06-17-51e16ebf-1
urandom-seed - 1.0-1
urngd - 2020-01-21-c7f7b6b6-1
usign - 2020-05-23-f1f65026-1
vnstat - 1.18-2
wireless-regdb - 2020.11.20-1
wpad-basic - 2019-08-08-ca8c2bd2-7
zabbix-agentd - 4.0.16-3
zlib - 1.2.11-3
so the packages should be integrated. I cannot test on this device but for other targets I've used in the past if the package is in the manifest it was included in the firmware image.
If you give the full commands you are using I can try with that and see if I can reproduce the issue.
That is the full command I used for testing. I see the packages being downloaded, installed and enabled but they are not in the build once I write it to the device and log into it after it has rebooted with the new version.
Oddly, yesterday, I re-ran the build doing nothing different what so ever and this time, the packages got installed. I cannot explain it. I'll try again in a day or two as I'm not near my build PC and will update this.
The problem was that the packages would show as being installed during the build but would not be on the device once I logged in.