In OO Workflow Designer 24.1, after a system property with an empty value (null value) is created, an error occurs. Subsequent editing cannot continue.

GUI Error is seen:
138200: {"message":"Unable to connect. An unexpected error has occurred. Check the logs for more details."}

In server.log an error is seen,
(AbstractResponseStrategy.java:88) ERROR - DefaultResponseStrategy: An error occurred - incident ID [fb79724b7fb0407392ffef890eaa4388]
java.lang.NullPointerException: null
at java.util.HashMap.merge(HashMap.java:1226) ~[?:1.8.0_372]
at java.util.stream.Collectors.lambda$toMap$58(Collectors.java:1320) ~[?:1.8.0_372]
at java.util.stream.ReduceOps$3ReducingSink.accept(ReduceOps.java:169) ~[?:1.8.0_372]
at java.util.Iterator.forEachRemaining(Iterator.java:116) ~[?:1.8.0_372]

This error prevents from creating projects with sensitive data set to null.

Open a support ticket asking for Hotfix HF_2157428