Text fields appears blank until I click into the field

I have a form created in Adobe Acrobat Pro DC that is sent out to clients for completion and submission.  It is usually downloaded from our website, completed, and then emailed back to me.

I have received some forms back where the text fields appear to be blank until I click in a text field, the data entered by the client then appears. If you then click off that field the text disappears again, so the text only appears in the field currently clicked in.

I have searched and a possible issue is that the client has used a 3rd party PDF viewer to complete the form, rather than Acrobat Reader, but it would be impossible to 'force' all of the clients to complete the form in Acrobat Reader.

There is a workaround by converting the file to a Word document, but this is far from practicable and wondered if there is something that I can do with the form to stop this from happening.

A portion of an example is attached. 

Cheers

Glenn