When NXT first introduced the feature that allowed us to assign types to attachments, a number of types were automatically generated (Excel.Sheet8, PDF, etc.). I would like to have the ability to inactivate some of these types and some other duplicative types generated by some of our users (grant, grant agreement for example).
The only Attachment Types available in NXT for me are those that were already in my RE:7 Table for Media Types... I would suggest a Support Chat to figure out why your NXT is creating new table entries rather than using those in your RE:7 Table.