This issue is occuring because of the declare expression ".pyLockingMode" in class 'Rule-Obj-CaseType'.
This sets the locking mode to optimistic when pyOfflineEnabled value is true. If the value is false, the locking mode is set to 'Default', which is incorrect.
Note:The issue has been fixed in later releases.
In order to fix this in 7.1.9, perform the following local-change:
Save as the declare expression into your ruleset and update it to set the locking mode to @java("tools.getProperty(\"pyLockingMode\").getStringValue()") in the otherwise section(i.e., if not offline). PFB. This will set the locking mode on casetype rule form correctly.