Assembly links to .3xf files can possibly change to .csb files when the assembly structure gets saved in DELTAGEN R2018. This might happen unnoticed by the user.
A fix for this problem is available from DELTAGEN R2018x and onwards. File links to .3xf files don’t change to .csb files when the assembly structure is saved in DELTAGEN R2018x and newer. We encourage DELTAGEN users to update to the latest available release of DELTAGEN.