The SRT subtitle parser wrongly aborts on a line containing a sole number as the text of a subtitle. Reproduced on Adobe 25.4.1 and also 24.6.5 LTS, seems independent of OS.
A minimal example to reproduce would be the following SRT file:
1
00:00:01,000 --> 00:00:01,500
First subtitle correctly parsed.
Even with two lines.
2
00:00:02,000 --> 00:00:02,500
Only this line parsed. In the year
2025
3
00:00:03,000 --> 00:00:03,500
This subtitle and rest of file ignored.
Due to sole number on the 2nd line above.
See attached screenshot for the results of importing the above SRT.

Just as a theory of what happens: The parser code treats the sole number on a line as an ID for the subtitle (despite not being preceded by a blank line) instead of as a part of the subtitle text. Then it aborts because the sequence of IDs is out of order or more likely because it's in the state of "new subtitle object started" and no timecode follows.