OnPremise PowerBI Dashboard Visuals (Date Slicer) Not Updating after PBI Upgrade

[RT3308]

Date Slicer not updating... old PBIDesktop version visual is line with ticks; new PBIDesktop version visual is line with balls.

PBIX file doesn't update the visuals to the new ones... re-creating the reports is not an efficient option.  Please help.

There are other visuals that does the same thing (updates not being applied to pre-existing and only applied to new ones)... this is even after setting "Use the modern visual header with updated styling options".