I've tried both the "Save All Entered Data" option as well as the normal save option after site login, both fail with "ERROR: Invalid Response".
I also tried manually creating an entry in My LastPass Vault, but the URL link does not work and I cannot launch the site from the UI.
I am using:
Google Chrome Version 77.0.3865.90 (Official Build) (64-bit)
LastPass Extension Version: Version: 4.34.0 - Built: Tue Oct 01 2019 19:48:28 GMT+0200 (Central European Summer Time)