If you are running into problems with Autoptimize;
- I'd recommend you go through the FAQ and specifically the "troubleshooting"-part.
- If you're still encountering horrible problems with CSS and/ or JS minification (e.g. white pages, although these should be gone as from 1.8.x), 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.
If you did all this and you're still having problems, you can file this as a new topic (i.e. do not reply to this post) in the support forum.