How to reproduce:
1. Open any project with the ProBuilder package installed
2. Open the ProBuilder Window (Tools > ProBuilder > ProBuilder window)
3. Hover over any text or icon in the ProBuilder window with mouse cursor

Expected result: Tooltip appears
Actual result: Tooltip appears only when moving the mouse cursor again

Reproducible with: 4.5.0, 5.0.4 (2020.2.0a21, 2020.2.7f1, 2020.3.30f1), 5.0.3, 5.0.4 (2021.2.14f1), 5.0.4 (2022.1.0b10, 2022.2.0a6)
Not reproducible with: 4.5.0, 5.0.4 (2019.4.35f1, 2020.2.0a20)

Notes:
- Tested with macOS
- Some versions require the ProBuilder window to be docked in order to reproduce the issue