Can anyone explain to me why my PoW mined coins do not show up when I search my wallet address in the block explorer?
My wallet says there are 44 transactions, but the block explorer only shows 4 of them - none of which are PoW mined. It only shows transactions where I sent coins from one wallet to another

One of your wallet may be on the incorrect fork
First find out at what block/height is the
block explorer.
then find out at what block/height are each of your wallets.
If any of your wallest are not in sync with the block/height of the block explorer that will mean that the wallet is on the wrong fork.
To correct the issue and get back on the correct fork you need to do the following.
https://bitcointalk.org/index.php?topic=683450.msg7966986#msg7966986