I run Yealink t28 phones and am having issues with the sidecar expansions. If I log into the phone web interface I can see a page 1 and 2 that I can apply contacts to, but on the freepbx admin side I only have the 1 page showing up.
That phone is EOL. So you will not likely get anything changed, but submit a support ticket in the Sangoma portal for EPM because it is a commercial module.