When cleaning up drawings i use to rise the numbering of the views logically.

However occasionally i ran into the message that a view number is occupied although it is not listed in 1 of the sheets.

Anyone have a clue if this can be solved?

Below an example. For instance Drawing View8 cannot be added (so i added an underscore).

When editing to change to "Drawing View8" the following message pops up:

Any help would be appreciated.