Error in Opening Merge Forms

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We utilize a merge form that pulls the candidate's name, the recruiter name, recruiter email, and current date by inserting the variables (ex {Candidate.FullName}) in the properties of the fields. When our recruiters go to use the form, it is giving them an error that it either cannot be opened or if they open it directly with the adobe software, it states that the file is damaged and could not be repaired.

 I've tried getting rid of the {brackets}, copying and repasting the variables in the instance something was upgraded, but neither solution has helped. 

I know this is also happening in Onboarding.