Hi @Giselem!
While Gerber is a standard, not every tool will implement it correctly, so there may be some trial-and-error to find out how to export correctly. Internally we haven’t used Ultiboard, so unfortunately I can’t help with specifics.
With many issues, you can typically resolve them by referencing our guide on debugging gerber file issues here - I suggest going through that first.
if that fails, our support lead @MikeL may be able to help you over the in-app chat.
-Matt