For older drawings with alphanumeric section designation (A1, B21 .... ), the section name can no longer be entered/changed alphanumerically.
Solution
In order to enable this, set the following preference:
"Preferences->Drafting->Drawing View->View Label->Secondary Indexing to "
Numeric".
Hardware/Software Configuration
Platform: na
OS: all
OS Version: n/a
Product: NX
Application: DRAFTING
Version: V1880
Function: DRAWING/VIEW
Ref: 002-8569891