Multi-select picklist fields not available as row groups?

Multi-select picklist fields not available as row groups?

Hello,

Has there been an update or change to the ability to choose multi-select picklists fields in row groups when customizing a report? I have several custom multi-select picklists that I need to be able to group records by, and now when I attempt to find them after creating a report, while they show up in my "Columns" list, they are not available as options in the "Row Group" list.

The strangest thing is that I have several previously-made reports that DO have these row group groupings by the exact same multi-select picklist fields that I am now unable to choose when creating new reports. Those old reports still work, and if I clone them, I can create different filters within their records and still have the same row groups sorted by the multi-select picklist field. However, if I deselect the multi-select field as my row group and then save the new iteration of the report, if I go back to edit it suddenly I no longer have access to adding that field back in for the row groups.

For the specific use case - 
My work records the sector and discipline of people who participate in our programs. I need to be able to run a report that filters contact record by the program name they participated in (for instance, to show only everyone in Cohort 12) and then groups those contacts with a count of how many people were in each sector (ex: 25 in Public, 14 in Non-profit, and so on). Sector is a multi-select picklist, and I have months-old custom reports that have the groupings by sector - but I can't create new reports that also group a different section of our participants by sector.

Any help appreciated, thanks.