Hey there, J – did you get this worked out? My amp pages tanked last week because of this and I had to just disable the CSS caching!
“Hello, First of all, sorry for the late response and the issue you are having
Is AMP extension activated? Try going to Page cache >Advanced >Reject User Agents, and enter those User Agents.
iPhone
Android
iPad
You can also add directories or subpages to the list.
Please make sure to update W3TC to the latest version as a lot of fixes have been applied.
If the issue is resolved after the update, please give us a feedback and we can close this topic.
Best Regards,
Marko”