Resolve 14 Beta 1 vs Beta 2 Optimized media issue

With the Beta 1 working in UHD timeline the Optimized Media function works ok.
Inside the Beta 2 with the same setting the Optimized Media function works random or doesnt work.
Checked with Prores file and DNxHR (and others codecs).
Noted also : installing the Beta 2 over Beta 1 (without uninstall the Beta 1) many crashs appears .
So seem to be necessary a total uninstall of the Beta 1 first.

UPDATE :

I found that there are some problems with the cache folders.
So it is better to clear all the contents of the cache directly from the operating system (OS windows).
Then it seems that the Optimized Media function works again.

UPDATE N.2 :

It seems that some problems remain also after clear the cache folder.
It seems that Resolve 14 Beta 2 forgot some Optimized Media files in totally random way between different session of the same project.