I just noticed that you had responded to me. For some reason, I thought the forum would tell me someone had replied. It seems not.
Anyway, I know about the export options and including the ICC profile. I see in re-reading my post that it wasn't clear that I'm trying to report a bug. Ticking and unticking this box has no effect. The company still says we are including the profile. This is why I mentioned the version numbers and platforms.
The software they are using seems to be something called Enfocus (Processed with 'SAGE'?). The error message it gives is "ICC based is used for transparency group".
Perhaps they are wrong and the profile is not included when we use this option. But checking/unchecking the box still results in a file that gives the above error at the printer, and the error suggests there is an included profile.
As I said before, we can use Illustrator to fix this problem in the file, but we would prefer to just use Affinity products for everything if we can. This error is preventing us from doing that.
If you could fix this somehow, it would be much appreciated.
Best,
John