Hi @akharns ,
Do you mean the Selected Fill property of the Top Data Table does not work, but work in other two Data Tables which have not set the Selected Fill property?
Based on the issue that you mentioned, I have made a test on my side, and don't have the issue that you mentioned. Please consider do not filter your two other Data Table records based on the Top Data Table directly, instead, store the selected item in your Top Data Table into a variable, then filter your other two Data Tables based on the variable.
Please make sure you have removed the formula within the HoverFill property of the Top Data Table.
Please set the OnSelect property of All columns in your Top Data Table to following:
Set(CurrentSelected, DataTable1.Selected)
and remove the formula within the HoverFill property of the Top Data Table.
Then set the Items property of your other two Data Tables to following:
Filter('DataSource', FilteredColumn = CurrentSelected.ColumnName)
If the issue still exists, please consider turn off the "Enable improved data table control selection and Value property" option within Advanced settings of App settings of your app, then add new Data Table controls in your app, check if the issue is solved.
Note: Please make sure you do not change the Selected Fill property of the other two data tables.
Best regards,