VS 2019 Strange One - Comboboxes highlight when TableLayoutPanel is Dock = Fill

Hi,

I've used this arrangement in other projects and not had this problem.

I have a TableLayoutPanel within a Panel, the TableLayoutPanel has multiple rows containing ComboBoxes, TextBoxes and DateTimePickers.

If the TableLayoutPanel is Anchored Top/Left I have no issues, when I set the TableLayoutPanel Anchor to Top/Left/Right or Dock = Fill when I run my application each ComboBoxes value is highlighted.

I've ensured the containing panel isn't being selected (but why would it only happen when docked?)

I've tried setting the ComboBox.SelectionLength = 0, and .SelectionStart = Text.Length didn't work but would like a better solution anyway.

If anyone has any suggestions it would be greatly appreciated, thank you.

Thank you.