Numbers don't add up when saving as a series, after choosing a start number greater than 1, it keeps trying to save my files with a non-consecutive number and the SW gives the feedback that the filename already exists.
Not sure what you mean by "saving as a series". Are you possibly running into problems while trying to rename on export? If so, can you share a screen capture of your export settings & file naming template?
Sounds like you mean you are renaming the images with a sequence number in the name. Please note that you can use different sources, one of them is the import number. The import number is the number of the import action however, not the imported image. That means it is the same for the entire import (and gets increased by one in the next import), so you can’t use that as a sequence number for images.