Bookmarks don't get saved or disappear for some users

[meganreckner]

A few users have written in within the past two months to report an issue with their bookmarks.

These users were able to add a bookmark and see it reflected on the individual course pages:
https://app.frontapp.com/open/cnv_bpirh8n
https://app.frontapp.com/open/cnv_btwzy9z

These users had existing bookmarks completely disappear:
https://app.frontapp.com/open/cnv_c3ixlxj - in this case the bookmarks came back without us doing anything
https://app.frontapp.com/open/cnv_cngysqv

[lsminter]

Here is another user with the bookmarks issue. https://app.frontapp.com/open/cnv_diiw807