I checked this when it was reported in Release 23.5.0.
Steps to reproduce:
1 Create a sequence from 1 or more clips.
2 Create a Static Transcription; do not create source transcriptions.
3 Create captions.
4 In the Project Panel, right click the Sequence, and "Open in Source Monitor."
Result: The clip name shows in the Source Monitor, but there is no video and no captions.
Expected: Sequence will show in Source Monitor. Absence of captions in Source Monitor is normal?
Workaround: After switching various sequences/source monitor/etc, the Sequence shows in the Source Monitor. Once it is showing, deleting the caption track and recreating does not result in the problem.
System info
Application: Premiere Pro (Beta) v23.6.0.56
OS: Windows v10.0.19045, RAM: 63.80 GB GB, CPUs (logical): 16