Signatures from multiple users on one pdf form

My company hires independent contractors who we have set up with a 'digital signing' system. The forms they need to complete are basic pdf forms they can fill in using reader. We have provided them with a drawing pad to allow for digital signatures to be drawn on the form. Each form requires 4 signatures from 3 different people (12 total). 

The guidance we have provided them says for person 1 to draw their signature and place it 4 times, then clear that signature and allow the next person to draw and place theirs. We have been receiving consistent feedback that once the second person is done signing, they are unable to clear the signature thus making it impossible for the third person to sign.

Personally, I have been unable to recreate this issue, but it has been mentioned so frequently I’m wondering if there’s something to it. Would there be any reason Adobe would freeze after placing 8 signatures? The drawing pad we have provided is the One by Wacom which requires no software. It simply provides a tool for them to sign digitally as if they were signing pen on paper. Any guidance or assistance on how to help would be greatly appreciated.