I had this issue, I believe caused because I use Ledger through Metamask.
How I fixed it…
Log out of everything & clear browser cookies.
Open metamask & switch to Ledger before opening Manifold app
Then I could see the tokens minted on my contract.
Note i also found patience as the next day it suddenly showed up even when i switched wallets - so was probably still doing something in the background. Thought would just add that.