I have a font from a typhographer designer,

The font includes several features such as tnum, etc.. and multilingual glyphs.

After testing the font in couple of programs. Some customers sent us a bug in Adobe Reader for mobile.

This bug shows some glyphs as "unidentified" while they actually exists - a picture is attached.

After working with the designer we found out that the reason for that is due to having the symbol "omSymbol" (which is the Yoga symbol).

We removed it and it fixed the problem (attached an image).

So - what comes out is that Adobe Reader for mobile probably throws exception and this gives the bug.

The bug only occurs in Adobe Reader as we tried several apps including Google Docs, OfficeSuite and more.
This bug occurs both on iOS and on Android.
This bug didn't occur only in one font (all the fonts that included this symbol effected other symbols).
The symbols that were effected were mostly Hebrew.