Problem solved.

This applies to FmL ver 5.1.1 and the Beta version of 5.2

Change the Type from Text to Integer and disable the "Searchable" option at the same time.

Once that is done the information is displayed and can be sorted properly.

Then, return to the Configuration and reinstate the "Searchable" option.

That's an interesting workaround. I did not have to do that, in my attempt to replicate the issue you've picked up.

Thanks for posting the solution to that issue. It might need some looking at.

I just imported all 11,000 records and once again the problem occured, this time I found another problem similar to the first. This time it wasn't solved by my previous solution.

However I found that if I change the Type from Text to Integer and I get the warning of "Note that this might cause an error, this is an unsupported cast!" that all I have to do is hit edit again and then save without doing any changes and the fields behaves like an Integer field.

So thats two solutions to my problem, just in case there should be anyone else with a similar problem.