@deyneko,
Sorry to hear about your pain. WordPress community is huge. You are free to go and find a solution that suits your needs. We can wish you only good luck with your venture.
The only reason why would the teaser message disappeared is because it most likely was defined for the API level too and because AAM 6.0.0 no longer has a separation between frontend, backend and API levels, migration script, by default, prioritized API access setting over any others as following:
array_merge(
$normalized['backend'], // Lowest priority
$normalized['frontend'], // Higher priority
$normalized['api'] // Highest priority
);
@gusray, we believe the cause was identified and more technical details are here https://forum.aamplugin.com/d/369-notice-undefined-offset-1-service-content-php-on-line-509.
Basically the problem occurs with posts and pages that had explicitly defined HIDDEN option. The fix is already in place and we are doing the final tests to make sure that all is covered properly.
It is going to be included in the official 6.0.1 release.
As for now, you would have to redefine access settings to your pages.