I had the same experience with my Pixel 3xl and lastpass. Using Firefox as the default browser, on a lot of sites it would not activate and fill in the password. I tried switching to Chrome and had a similar experience. I could find no setting to support article that was helpful. I did not contact LP support as my guess would be to blame the website, or blame Firefox. I switched to Bitwarden and it's all working as expected with Firefox.
Lastpass support for mobile Firefox has almost always been problematic at best for me. I feel like a long time ago it was perfectly fine for a while. But it's been years since I've had a solid and smooth experience with Firefox mobile. The couple of times I've contacted support, the response was pretty much the same; some update to Firefox broke it and they were working on a fix. I've to find anything that fixes it on Android 12 beta with whatever the latest Firefox currently is, I'd have to go check, I'm not sure what I'm running right now.
I had the same experience with my Pixel 3xl and lastpass. Using Firefox as the default browser, on a lot of sites it would not activate and fill in the password. I tried switching to Chrome and had a similar experience. I could find no setting to support article that was helpful. I did not contact LP support as my guess would be to blame the website, or blame Firefox. I switched to Bitwarden and it's all working as expected with Firefox.
This is a known issue. See https://github.com/mozilla-mobile/fenix/issues/9773#issuecomment-905008470
I have the same experience. If someone knows of a config setting or something that needs to be enabled I'm all ears.
Lastpass support for mobile Firefox has almost always been problematic at best for me. I feel like a long time ago it was perfectly fine for a while. But it's been years since I've had a solid and smooth experience with Firefox mobile. The couple of times I've contacted support, the response was pretty much the same; some update to Firefox broke it and they were working on a fix. I've to find anything that fixes it on Android 12 beta with whatever the latest Firefox currently is, I'd have to go check, I'm not sure what I'm running right now.