Font wouldnt stay uploaded in Unity Playworks or gets removed from Unity Playworks after refreshing

This could be to do with the font file being invalid.

Possible solutions:

• Check the file size, if its very small, a few Kb for example, its likely that it's not valid.
• Open a font preview app to see if it shows valid characters. On Mac this can be done by double clicking the font to open the Fonts application. (Example of this below)