I’m having the same problem, trying to deposit ETH into a staking contract and it is failing. M1 Mac Air, tried both Firefox and Google with the same results.
Closest I got was seeing the ‘select an account’ dialog, which had my Ledger account ticked, but the Unlock button is greyed out, and nothing I did would enable it.
Have followed the checklist at articles/360020394612-How-to-connect-a-Trezor-or-Ledger-Hardware-Wallet so everything should be correct
Update: I solved the problem by using Chrome and using the bridge to Ledger Live. To enable this, In metamask go to Settings: Advanced and scrolled down to the switch for Use Ledger Live