Text field fonts reverting to default

Hi,

I am using Adobe Acrobat Pro DC to create a PDF form with multiple text fields. I have set the font for each text field to Calibri size 12 in the Text Field Properties -> Appearance tab.

When prefilling the form, all text fields display correctly. However, once the form is sent using 'Send for Signature', several of the now-flattened text fields revert to the system default (Helvetica).

This problem only occurs to some of the text fields, not all.

I have tried:

• re-creating the affected text fields, with new names, different font faces, different font sizes etc.
• right clicking an unaffected field and clicking 'Use current properties as new defaults'
• duplicating text fields that aren't affected (using CTRL + drag) and then renaming.
• creating an entirely new form, without field auto detect, creating everything manually and saving as a different filename.
• pre-filling using the online Send for Signature interface instead of directly from Adobe DC.
• using JavaScript to loop through text fields and change the font.

None of the above attempts to fix the problem have worked. Can anyone please suggest a fix? The font is crucial to our company brand.

Kind regards,

Alex