Acrobat Form - Expected a dict object failure

[SBrad249]

Hi everyone, and thanks in advance to anyone who can help...

I have created a form (a simple single-page table, designed in Indesign and exported as a PDF).

I have created a form using this PDF using Acrobat Pro DC... it has the following fields;

At the top is a drop-down list in the 'site' box with a list of sites.

To the right of this is a date field that brings up a drop-down calendar.

Under this are the following columns;

1. Name - a free text box
2. Hours Worked - a numerical entry box to 2 decimal places
3. Annual Leave hrs Worked - another numerical entry box to 2 decimal places
4. Total Hours to be Paid- a numerical entry box to 2 decimal places (which has an automatic value entrty based on a sum of the previous 2 columns)
5. Managers Signature - a free text box

At the top right are two 'action buttons';

The 'RESET' button resets all fields to the blank page you see above (with the exception of the site and employee name fields (to save the relevant sites having to re-imput staff names)).

The 'SUBMIT' button submit's a form as a full PDF using a mailto: function to an email address.

Everything works except the SUBMIT button. When clicking it the following message appears;

'Expected a dict object'

I have looked through the forums (and other forums) and have not found a solution that works.  I have tried renaming the file, deleting the submit button, renaming the file and re-introducing the button, saving as an optimised file etc...

I have a submit button on another form that I have created and the check-boxes and mailto: addresses are identical.

No third-party apps were used, only Adobe Indesign and Adobe Actrobat Pro DC.

Is anyone aware of a possible solution to this please?

[SBrad249]

Semi-solved this (by way of a workaround)...
Saved the document (without the submit field) to Dropbox via the iMac I use, opened the file using my Apple laptop (both vesrions on both computers are up-to-date via CC).

Added the submit button on the laptop (in exactly the same way that I had done on the desktop), and saved as a different version to Dropbox.

Opened the updated document from Dropbox on the desktop... worked fine.

I have no idea how or why.