technician signature comes as negative randomly

Hi Experts,

I would like to have you input on following scenario.

There is a situation where task gets completed from mobile with technician signature for some of the tasks randomly technician signature value comes as a negative value.

As follows

I have checked the server logs also but could not find any info on any error causing this issue.

I feel like this can be a sync failure. 

It is really appriciated if you could provide any input on this how to track the issue. 

Thanks,
Heshala.