Hi! You’re welcome! 
Can you mark the post that helped you as solved, so it would be easier to find in case other players encounter the same problem?
Also, something that might help you in the future as well. If the scans come out clean and uninstalling/installing doesn’t solve the issue, then it might be something wrong with the registry (registry is where Windows stores settings of a program).
To fix up registry issues you can use AVG Tune Up, which I assume it was recommended by Blizzard support, according to this post:
CCleaner does the same job, but I assume AVG Tune Up must be better for Stacraft, if it was indeed recommended by support.
Before using any of those tools create a restore point in case something goes wrong with the registries, so you can restore Windows from an older state.
In general, registry tools are not recommended, because they can make your system unstable or maybe it can break it up completely if something goes wrong. But if support recommended it, they must know what they are doing.
Having messed around manually with registries in the past, instead of using any of those 2 programs, I’m using a monitoring program like Total Uninstall, which tracks down where each file, registry is created for the program during installation and it shows that to me in a clean interface. That way you I can decide for myself what leftover files/registries I can remove. Of course, before using this tool, I’m creating a restore point
as well.
Links to all tools/info here:
https://www.avg.com/en-ww/avg-pctuneup#pc
https://www.ccleaner.com/
https://www.martau.com/
https://pureinfotech.com/create-restore-point-windows-11/#:~:text=Once%20you%20complete%20the%20steps,a%20backup%20of%20the%20Registry.
https://answers.microsoft.com/en-us/windows/forum/all/discussion-how-to-create-a-system-restore-point/91aada34-ae98-4007-a19b-15ce6edb41bd
https://support.microsoft.com/en-us/windows/use-system-restore-a5ae3ed9-07c4-fd56-45ee-096777ecd14e