It might be a misunderstanding on my side (or a wrong usage), but to me it seems that even though a clip is marked as favorite, it will be moved to the Recycle Bin if a time rule (e.g., clip too old) applies.
To me, that seems counterintuitive. 'Favorite' to me means 'never get rid of this clip'.
Because I kept 'losing' favorites that way, I now have no purge rules based on time activated, so that my favorites stay, and I clean the clips manually.
A rule like 'purge clips based on time rules, but exempt favorites' would seem enhancing my productivity (even more than it has already been by this great tool).