- If you are running into problems with Autoptimize, I'd recommend you go through the FAQ and specifically the "troubleshooting"-part.
- If you're encountering horrible problems with CSS and/ or JS minification (e.g. white pages), these could be due to the newer CSS/ JS compression components. If that is the case, you can easily switch back to older minification components, by adding this to your wp-config.php;
The "legacy minifiers" will remain in Autoptimize "for ever" and changes to wp-config.php are not affected by core-, theme- or plugin-upgrades so you should be good to go.