Trying to open a second ontology does not bring up open-file dialog box

[samsontu]

On 14" M1 MacBook Pro running Sonoma 14.2.1 and Protege 5.6.3, when I try to open a second ontology, Protege asks whether to open the ontology in the current window. Responding either Yes or No results in no action, i.e. no dialog box to select ontology file to open. Responding No results in Log window having the following added. Responding Yes doesn't add anything to the log window.

INFO 10:09:02 OWL API Version: 4.5.26.2023-07-17T20:34:13Z
INFO 10:09:02 ---------------------------- Disposing of Workspace ----------------------------
INFO 10:09:02 Saved tab state for 'Individuals by class' tab
INFO 10:09:02 Saved tab state for 'SNAP SPARQL' tab
INFO 10:09:02 Saved tab state for 'Entities' tab
INFO 10:09:02 Saved tab state for 'Active ontology' tab
INFO 10:09:02 Saved tab state for 'DL Query' tab
INFO 10:09:02 Saved workspace
INFO 10:09:02 Disposed of 'Individuals by class' tab
INFO 10:09:02 Disposed of 'SNAP SPARQL' tab
INFO 10:09:02 Disposed of 'Entities' tab
INFO 10:09:02 Disposed of 'Active ontology' tab
INFO 10:09:02 Disposed of 'DL Query' tab
INFO 10:09:02 Disposed of workspace
INFO 10:09:02