I see the version of Marginalia installed on this site is quite old - I think it dates to last December. I have implemented some significant bug fixes and a number of improvements (particularly supporting sharing annotations between users) since then.
At the moment, I am working on a new release to patch some bugs from recent reports (nearly all involve IE). It's close to ready; I'm currently doing IE sanity tests[1]. Once I'm done, I will recommend updating this site.
[1] IE always tests my sanity; sometimes I wonder why I decided to support it.