Why can't Protobuf Support find proto files?

Question

Java

I work in intellij IDEA. I created a .proto file and it is not highlighted by anything, I suggested the idea of ​​installing the Protobuf Support plugin, I installed it. The file was found and indexed as type proto. But then some hint popped up, I didn't read it to the end and pressed the "Revert" button and the file is not highlighted again. Tried to reinstall the plugin, reboot - nothing helps. What could have happened and how can such changes be returned to Local History is also missing.