Please refer to the article below: 
https://answers.laserfiche.com/questions/94427/No-permission-to-mobile-upload-electronic-documents-yet-no-problem-with-image-files-or-other-clients 
"Hello all, 

A case was opened with Support regarding this issue. It seems to be a bug (SCR 142155) which causes this when Laserfiche Mobile Server 10 Update 1 is in use with Starter Audit Trail. The workaround seems to be disabling audits of "Export and Print" events from the Administration Console > [Repository] > Auditing > Configuration. 

Thanks for bringing this to our notice." 

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I was unable to find any resolution for SCR 142155 and would like to know if this bug has been addressed in 10.3.