P: Save for Web - Unknown Operating Error with # in the file name (macOS)

Photoshop version 21.1.2 on mac mojave 10.14.6

If I open a file which starts with an '#', I can't export it nor save it for web legacy.

Thanks for the file. I've logged an issue for engineering to look into this.

Thanks Tom, 
It happens when Im trying to hit Save for Web (as a short key command or from File -> Export -> Save for Web

you can find file here:
https://drive.google.com/file/d/1lKtoRlL3MAtSTeFXwX9oK6l8wKmR9gBV/view?usp=sharing 

I actually might found potential reason - we tend to have templates starting with "#####_" in filename, and sometimes place them as smart-objects in our designs. And while PS 2019 saves for web fine files with that name, but PS 2020 is having issues with it, when I renamed my file and removed "#####" it seemed to help.

But would love to find if you have better insights to this.
Thanks!

Nadia-Can you send me a file that shows the bug? I'm not seeing the problem. Also when does the error occur? When you try open Save for Web or when you save files from Save for Web?
-Tom Attix