This issue only occurs with -audiomixer passed into the Engine (4.23) and in 4.24/4.25 where it is enabled by default.
The user tried deactivating and reactivating Time Synth component to pause it, but it doesn't work. It doesn't resume playback of the clip, but it does continue to count quantization. It seems like Time Synth looses loaded clip on deactivation
This was reported and tested in 4.23.1 (CL-9631420). This was reproduced in 4.24 (CL-10570792) and Main 4.25 (CL-10611905)
Results: After Activating TimeSynth again audio Clip doesn't resume playback.
Expected: TimeSynth resumes playback of the last loaded TimeSynth Clip from the point where it was Deactivated. TimeSynth clock resumes ticking (not restarts), Clip resumes playback (not restarts)
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-85566 in the post.