Group headers lost when filtering a grouped list

Question

I have a custom view formatting a list of sites, grouped by a heading that contains a combination of data (calculated field.) When SOME of my users apply a filter - the grouping is lost and we're left with a stack of cards for the sites - no grouping context. Anyone know why the group heading get lost? NOTE: this is only happening for a few people (but of course, they're the most active users.)

This is what is SHOULD look like. The customer names/contact have been blurred.

The field used in the group is a calculated field of Customer and Contact so that I can get both values into the heading.

Answer 1

Solved. The issue is somehow related to the "Offline Client Availability" setting. Setting this flag to "No" seems to solve this issue of display wonkiness.

Don't know why --- just know that it does.