I bought the Home Assistant Connect ZBT-2 and added it, but it's added as 'other network' and not preferred network. The support pages are a bit sparse.
#Home Assistant Connect ZBT-2 matter not preferred
cosmic haven
autumn iron
It usually means that the Thread "Integration" is not talking to the OTBR. This is usually handled auto-magically in an HAOS environment, but if not, trying going into the Thread Integration and see if it is asking for a URL.
gray bane
there's been a few time where people have reported an issue where the integration didn't get properly set up - restarting home assistant to retrigger the discovery sometimes helps