Hi Polina, cheers for the info on the “subtract opton” working best. I am always curious in these cases though as to what “best” means.
For the ref sacn that is giving you that error, I would suggest opening using the “open as” option and then save the data as MRUI format. This should avoid the issue when selecting it for the correct with ref file. (this assumes it can be opened with the “open as” option).