Solved in the same way, but I had to disable and re-enable the fingerprint support in the account settings.
LastPass, which I pay since years, became ridiculous. A turtle would be faster than LP developers...
I believe they might have very recently removed the "use improved save and fill" option; Chrome plugin version 4.109.2.
I finally dumped LastPass for one of its competitors. I've been less and less satisfied with the service as time has gone by, and the recent (and not so recent) security breaches are completely unacceptable. But also contributing to my decision is the fact that this two-year-old—and counting—issue still hasn't been resolved. Two years! Give me a break. I'm glad to say, though, that this is the last time I'll feel annoyed by it. I'm free!