Expression.Error: We cannot convert the value null to type Logical. Details: Value= Type=[Type]

Hi,

I'm getting the above error and I've seen other posts on this, but can't seem to find a solution, so wondering if anyone can help in pointing where to find this, because it's only just appeared and bizarrely only happening on desktop, on the online version which is refreshing via a gateway every day, there is no error message at all, it refreshes fine, but on desktop no dice.

I thought it was to do with emerging some other tables so I deleted those emerging and in preview the error went away, but each time I take one more merge away I try and load and the error pops up again.

Does anyone have any pointers of how to track down this rogue line, based on the error message? Its a very big table I'm using so loads of lines to go through.......

If there is anything I can post to help please let me know

Thanks