I'm unsure about is this related, but what I found out the difficulty went so high for PoW at the very start that GPUs found most of the PoW blocks. Likely half of the found blocks are PoS mined if looking into the explorer.
I can check is the wallet having timeoffset, because its been up and running from very start, restarted it once.
If there is time drift, I have to shut down the stratum for the time when I restart the wallet and wait it to synchronize fully before firing stratum up to make sure there won't happen chain forking.