Multicam edit need help

I am editing multicam 4 k media since years, never had problems when editing in proxy. Now I have a project, that is basically the same as all other, where no problems appear , only that this has only half the angles I usually work with, and all of the sudden editing proxy is impossible, as soon as I try to play the clip (to find the proper cut) I get the beachball for at least 2 min. I have tried the proxy media in QT, it plays fine.. Other events don't have that problem. I did not change anything in the system. Any idea how to fix this? I am not panicking close to deadline but close.

Thanks

Open background task window, is it still generating proxies or anything in the background?

There are no background tasks. Strange is that it looks like it needs rendering, while NOTHING was attached to the clips....

… give FCPX a slap on the beachhead and reset prefs … solves many 'hiccups'

Karsten Schlüter wrote: … give FCPX a slap on the beachhead and reset prefs … solves many 'hiccups'

Hi did that... no change. any other idea?

First, be sure Background Rendering is tuned OFF, and NEVER turn it on again.
In the Browser, select the Library, go to the File menu, to "Delete Generated Library Files" and trash ALL render files and Proxy media. Regenerate your proxies if you have to.
Next, verify all hard drives have at least 15% of each's total capacity left as free space.