On several of my microG-based ROMs I found I needed to manually replace microG when it was not possible to update via normal means (like when I was using modded builds during their “down period” or get signature mismatches).
It’s a simple matter of replacement while in TWRP. Copy the new microG apk to /system/priv-app/GmsCore/ directory. Copy/save/backup GmsCore.apk if desired, then delete it. Rename new microG apk to GmsCore.apk. Give it permission 644 (rw-r-r).
EDIT: Oops, forgot to mention. On A/B system-as-root devices the path would be /system/system/priv-app/GmsCore/.
On my ROMs I also had to make sure there were no updates in /data/app/ but that’s not an issue on /e/.
Maybe wipe dalvik and cache for good measure. Reboot into ROM. Check app permissions, just in case, then run microG Settings. See if all is still good, checkboxes and all that.