This is a simple problem with an infuriatingly non-obvious solution, and it highlights a real blind spot in how Excel handles data outside the Data Model. The user here has done everything right: they built an index column that logically orders their fiscal quarters, and they correctly identified that Power Pivot offers a "Sort by Column" feature that makes this work seamlessly. But the moment they step back to standard Tables and Pivot Tables to support Mac users, that clean logic breaks. The slicer defaults to alphabetical order, turning "FQ1'26, FQ2'26, FQ3'26, FQ4'26" into the nonsensical "FQ1'26, FQ1'27, FQ2'26, FQ2'27." It feels like a regression, and in many ways it is.
The practical fix is not hidden in the slicer settings or the Pivot Table options. It lives in the source data itself. To restore order without Power Pivot, you must sort the underlying table by that index column *before* you create the Pivot Table and slicer. Excel's standard Pivot Table respects the sort order of the source data for text-based fields when it first builds the cache. If your table is sorted ascending by "20261, 20262, 20263," the slicer will display "FQ1'26, FQ2'26, FQ3'26" in that correct sequence. You can then disable the "Sort Ascending" option on the slicer to lock it in place. It is a fragile workaround, any refresh that rebuilds the cache from an unsorted table will break the order again, but it works.
What this reveals is a gap that should not exist. The user has the data structure to solve the problem; they have the index column. They are not asking for a new feature; they are asking why a basic sorting dependency that works in Power Pivot vanishes the moment you use standard tools. For organizations with mixed platforms, this is a daily friction point. The solution should be as simple as telling Excel "sort this slicer by this other column," regardless of whether you are using a Data Model. Until that functionality arrives, the workaround is to sort your source table religiously and treat that sort as part of your data preparation checklist. It is an extra step, but it is the one that restores order.