I have a clue what is going on here, but just to be sure, what version of the WR1043ND are you using (v1, v2 or v4)? What was the OpenWRT version where it did work? Not sure, but I think it's due to the ar71xx migrating the ath79 target. So for OpenWRT 19.07 you can download 2 different images for your device (ar71xx, ath79). Maybe there's a difference between the targets, but I can't check since I don't know which revision of the WR1043ND you are using.
Yeah you can flash the ar71xx target to get those LAN leds working again (see my previous post). However, the ar71xx is deprecated and will be removed in future release in favor of the DTS based ath79 target (perhaps in OpenWRT 20?).
Someone needs to add LAN led support for your device in the ath79 target. It's not in the the DTS used for your WR1043ND v2. It is included in the WR1043ND v4 DTS. Maybe I look into it if it isn't already included in the master branch, and after I ported my own router from the deprecated ar71xx to ath79 target.