I have looked at debug.log and found no deep reorg. I think the reason of disappeared mint is a display problem.
I use a R-pi to mint and sync my laptop that has hte same wallet every several days. The last sync was May 18. In this sync the laptop showed some new blocks found by the pi first then they disappeared for some reason. I posted OP and turned put the laptop to sleep. After some hours I turned on the laptop again, the client showed the missing blocks again. There is only one WalletUpdateSpent found spent unit ... for every new found block (identified by the height) so I guess the client really only received the new blocks once. The disappearing is due to delayed display of new-found blocks of the client. This is still strange but not serious.