This worked for me!
Same issue – Space bar won’t make it play. Clicking the play triangle won’t make it play either. Basically, I can’t play the sequence or a single clip at all!
I tried re-starting, etc. = nothing.
Just went to Premiere Pro>preferences>audio hardware>Built-In Output> OK
And it started playing again! Then I switched back to my external audio (Insignia Sound Bar) and it is playing fine again.