This issue happens when using Kie server without BPM capability.
If Kie server is registered in Workbench using websockets then Workbench tries to register queries into Kie server even if Kie server's server template has BPM capability disabled.

In case websockets are used then KieServerIntegration returns WebsocketKieServerClient without capabilities check [1] . This client is then used for retrieving query client [2] to be used for query registering.

[1] https://github.com/kiegroup/jbpm-wb/blob/aeefe8e39d299ed67846518fa7531d61ea2fd1d0/jbpm-wb-kie-server/jbpm-wb-kie-server-backend/src/main/java/org/jbpm/workbench/ks/integration/KieServerIntegration.java#L129
[2] https://github.com/kiegroup/jbpm-wb/blob/aeefe8e39d299ed67846518fa7531d61ea2fd1d0/jbpm-wb-kie-server/jbpm-wb-kie-server-backend/src/main/java/org/jbpm/workbench/ks/integration/KieServerDataSetManager.java#L119