This was (is) a problem with the old Oly ZD 12-60 SWD lens hood. For whatever reason that one over time would start to "stick" and I have read a number of reports of users who have actually broken the front plastic piece off their SWD because that hood would eventually act as a filter wrench, except it was the front of the lens rather than a filter that it would b wrenched off. On mine, I periodically spray a silicone spray on a paper towel then wipe down the inside threads of that hood to keep it from sticking.
Mine was sticky too. I used the same paraffin wax treatment I used for the JJC 60 macro hood. I rubbed the bayonet lugs and the hood grooves with paraffin, and had no problems thereafter. The hood stayed on when mounted, but was easily dismounted. Try it.