I don't have either a DIN-CEN-CN-2 nor the CAEN-BLOCK-CENCN-2-POE in my program. I do however have a?CSA-PWS10S-HUB-ENET, and it very possibly that I only saw this pop up on this project after I added that device to the software.
Odd that I saw this in the past though on one CP3 which had no such Cresnet extenders, and it went away only after a restore. Oh well, hopefully it'll get fixed then in a future Toolbox release.
