Since upgrading to the 1.3.0 release of the plugin any new node that we add as slaves have the following effect on the build.

[CCUCM] ClearCase UCM Plugin version 1.3.0
[CCUCM] Allow for slave polling: true
[CCUCM] Poll for posted deliveries: false
[CCUCM] Forcing deliver: true
[CCUCM] No Baselines found
[CCUCM] Pre build steps done
[CCUCM] Finished processing; the baseline is null, this could pose as a problem!

Other nodes that have been migrated through the version 1.2.0 of the plugin behave normally for the same build.

Additionally a fresh install of Jenkins with the latest plugins causes the same issue as a new node.
During the upgrade from 1.2.0 to 1.3.0 I did note/remember that there was managed data that was no longer relevant around the baseline topic however this was not noticable from the UI i.e. I did not spot anything missing so ignored.

We are using the standard settings that the documentation mentions to apply i.e.

At the System Level for the plugin I have:

Allow polling on slaves - unchecked
Poll for Posted Deliveries - unchecked

Job Level:
Promotion level - ANY
Load modules - All
Polling - Poll Self
Create baseline - unchecked
Recommend baseline - unchecked
Make tag - unchecked
Set description - unchecked
Force deliver - unchecked

Plus the required:
Stream
Component
Build Project
appropriate for our repository.