"Hold on" popup hangs on "Importing assets" when changing script if Visual Studio is opened while in Play Mode

How to reproduce:
1. Create a 3D project
2. Create and attach a script to anything in Hierarchy
3. Open the script and add a line of code (e.g. "int d;")
4. Click back on the Editor in order for recompilation to begin

Expected result: Recompilation occurs and the "Hold on" popup closes
Actual result: "Hold on" popup hangs on "Importing assets"

Reproducible with: 2020.2.4f1, 2020.3.2f1, 2021.1.0b5, 2021.2.0a11
Not reproducible with: 2018.4.33f1, 2019.4.23f1, 2020.2.3f1, 2021.1.0b4

Note:
1. Can reproduce in two ways, before opening the script entering Play Mode, or without entering Play Mode
2. Can reproduce by just opening a Script
3. If in Preferences of External Tools of IDE is set to "Open by file extension", doesn't seem to reproduce after choosing this setting and reloading Unity and VS.