Bear in mind that the command "Update clients" will only prompt the clients to launch LiveUpdate on their next heartbeat in. You cannot prompt a heartbeat (which is how the client checks for content from the SEPM) in this way.
The only way I can think to trigger the clients to heartbeat in is to have the communication mode set to Push (rather than Pull), give it time for that Communication Settings change to be picked up by the clients (based on previous heartbeat schedule), then make a minor change to any policy. This will prompt the client to heartbeat in and it should pick up new content at the same time.
You wrote:
I have an isolated environment with a SEPM server and some clients.
I update the SEPM using a .jdb file.
I don't have access to a LiveUpdate server. (Isolated)
I want to update the defs on my SEP clients and LiveUpdate is not an available option since I don't have a LiveUpdate server and don't want to add one.
How do I force a SEP client to update its defs?
So this situation applies to your original post? Are you saying that the only way your SEPM gets content is with a JDB; that the SEPM itself never gets content from Symantec LiveUpdate's servers?
The SEPM is at version Dec 20th
Are you seeing that on the Home tab, under Latest on Manager? (What version of the SEPM and SEP clients are you running?)
If there is NO LiveUpdate server configured for use and the clients do not have access to Symantec LU servers, then the way forward is with sylink debugging. It will demonstrate why the content delivery is failing to the client.
(BTW, the only thing a JDB will update is virus definitions. If you're concerned that other types of content besides Virus and Spyware defs are not updating on the clients then it's because of the JDB file updating the SEPM.)
sandra