I have the a few phones all of which have been suffering with biometric issue for many months but after reading the post from another contributor I have been able to get all phones working again after the March security update was installed
1. Open Lastpass on Android
2. Open the menu icon top left
3. Press the gear icon bottom left
4. Press Actions
5. Press Clear LastPass Cache
6. Press Refresh Vault
This has resolved the issue on Pixel 4a, Xiaomi Mi A2 and Xiaomi Mi A3
I hope this helps someone else
Same issue here on OnePlus 7 Pro with Microsoft Edge browser. My phone has an on screen fingerprint reader.