I've used OpenWRT 18.06.01 for a while on a Raspberry Pi 3B as a WLAN AccessPoint successfully, so far. Until two days ago. I've got new RaspPi 3B+ and looked whether OpenWRT is supporting the new hardware. OpenWRT claims that since 18.06.00 the Raspberry Pi 3B+ is supported. Downloading and flashing the Image onto an SD card is quickly done - but on all devices I have at hand, the image doesn't boot and the green LED is flashing. This happens to all the RaspPi3B+ I have at hand. 18.06.01 is de facto not capable of being used with this sort of device.
I tried several snapshots up to today's snapshot OpenWrt SNAPSHOT, r8639-99e2121. They boot, so far. But WiFi is unusable as AP. While the latest snapshot, as of yesterday, resolved the problem of WiFi adapter not being detected, now the adaptor is being detected and it seems to work anyhow as a "client", but it is non functional as an AccessPoint/HotSpot, also configured explicitely as AP.
So far ... this is embarassing.