I tried to use the extension listed here: BlockingCallbackTransform The blocking functionality works, but the context stopped working on my callbacks. Instead of giving the name of the trigger for ctx.trigger_id, the blocking functionality causes it to delivere a different value instead.
I’d like to use the extensions, but I’m concerned that I can’t because the trigger id doesn’t appear to work.
That is true. Since the transform uses a separate triggering mechanism, the ctx.trigger_id will refer to that mechanism, not to the component that triggered the callback initially (which might be what you expected).
Is there any way to use both the blocking callback transform extension and know what triggered the callback? If not, is it possible to setup a chain of callbacks instead?
Not with the current implementation. But I believe it would be possible to add support for that ‘feature’ 
Does blockingcallback block all other users from that same endpoint during the calculation of the one, or just that specific session?
Just that specific session
I have started working on a solution. Could you try to see, if dash-extensions==0.1.8rc1 resolves your usecase?