I have not tried a max transaction. I think my issue is different and happy for now to discuss here, so others can comment if relevant. I use the Apple version of the app.
I also have one new observation. I just transferred 10 Algos from account 1 to account 2. Previously account 2 had a balance of zero. After the transfer, account 1 is receiving reward updates again.
So it seems to me like there is some hierarchical setup between the two accounts, i.e.
If I delete account 2, account 1 cannot be accessed anymore. If I re-add account 2, it works again.
If account 2 has a balance of zero, account 1 does not earn rewards (or at least not showing an update for them, i.e. always showing ‘you have earned zero rewards since your last transaction’).
Please let me know what other info I can provide to help sort this out.