But is the issue caused by the plugin or by the code you are inserting?
Please use debugging functions to disable inserted codes:
https://adinserter.pro/documentation/debugging#back-end
When you disable the plugin you also disable insertion of codes. So this test does not prove anything.
Keep the plugin activated and disable inserion of header, footer, blocks and other codes.
If the problem goes away then very likely it has nothing to do with the Ad Inserter.
Gradually enable codes until you find the one that causes issues.
You can also test previous versions:
https://www.ads-software.com/plugins/ad-inserter/advanced/
Do not change settings, only temporarily install previous version to see the difference.