With the web clipper loaded you can no longer use the keyboard to change the state of checkboxes.
See https://github.com/mui-org/material-ui/issues/24741 for more details.
Basically the web clipper causes accessibility bugs if it is loaded.
As an aside, I love how the email address associated with the extension in the Chrome web store is useless. Good job, there.
--
edited from a version that implied that the clipper was only incompatible with the material ui library.