If you suspect that a template has become corrupt, it is possible to validate and repair it. From the main source
You can access the functionality to work with Templates by going to File and selecting 'Manage Templates'.
Note: you can also access 'Manage Templates' by going to 'Help', then 'About Importacular', clicking on 'Advanced' in the bottom left hand corner, then selecting 'Manage Templates'.
You will then be presented with your Manage Templates window:
Select the template that you want to work with.
From the Template Integrity menu select the desired option:
They both perform a similar function but check an external template will allow you to check the integrity of a template that has previously been exported to a file where check selected template allows you to check the integrity of an existing template.
Importacular will report back if there are any errors within the template. Likely errors include mismatches between internal id values. For example:
You are given the option to repair the template. When it has been repaired you will be notified. This should only take a matter of seconds.
If there are no errors to report you will be shown the following message: