Premiere silently removes frame hold segments and changes previously edited title text

Premiere is becoming increasingly unreliable for me: at some point while I am working on a project, it removes or changes work I have already completed, without any warning.

I have experienced this with two types of edits:

1. Disappearing frame hold segments

For some time now, segments created using “Insert Frame Hold Segment” have disappeared from my timeline. The actual clip segment created by that command goes missing after I continue working on the project.

2. Title text unexpectedly changes

More recently, I have experienced a similar issue with titles. I created a sequence of different words, each displayed for 7 frames, with the final word remaining on screen for 3 seconds.

Initially, everything is correct. Later, five of the words are no longer there: their text has been replaced with words from some of the other titles.

When this happens

I cannot identify the exact trigger. These edits are within the first 10 seconds of a roughly 25-minute sequence. I continue working elsewhere in the sequence and only discover the changes when I return to the beginning or export a version of the video.

I am not deliberately deleting those segments or changing those words. These are completed edits that were previously correct.

Expected result

Completed edits should remain exactly as I left them unless I explicitly modify them.

Actual result

Previously correct frame hold segments disappear, and previously correct title text changes unexpectedly.

This is more serious than a playback glitch: I can no longer trust that completed sections will remain intact while I work on the rest of a project. Having to repeatedly check an entire 25-minute sequence for unexpected changes is extremely frustrating and time-consuming.

Could Adobe please investigate this? Please let me know what project files or other evidence would help identify the cause.

Premiere version and build: 26.5.2 (Build 5)
Operating system and version: macOS Golden Gate 27.0.1
Hardware / GPU: MacBook Pro M4 Pro
Sequence: 59,94 fps / 3840x2160