While I doubt the speculation that I put in the title is correct, from time to time my default cache partition (10MB trial) gets emptied within less than an hour.
There are about 20 keys in there, each taking up around 600 bytes. I am setting the TTL to the maximum 48hr value, therefore the cache cannot be dying. I am not able to pinpoint the whenabouts but so far I have seen it happen after running unit tests, executing an anonymous block, and refreshing the Org Cache Diagnostics page. All of them hit the cache.
With regards to the Diagnostics page my experience has been bizarre: I populated the cache about 2 hours ago with 19 keys, then just 5 minutes ago when I refreshed the Org Cache Diagnostics page 10 of the entries were gone. I refreshed the page after 1 minute and this time got an internal server error! With the next refresh the error was gone but so were all the remaining values in the cache. There were no code changes, deployments, or unit tests during this period.
So my question is, are there any other reasons beside those documented on the official Platform Cache Limits page that might be contributing to this seemingly random eviction of my values?