Scene Delay Changing

[JakeMM]

Sketchup 2018. Exporting a video - 3.5 second transition time, 3 second scene delay. Using a MacBook Pro.

Export works as it should, but when it gets near the end of the export, it suddenly skips and says it's complete.

When I look at the finish video, it does include all the scenes and all the transitions, but for the last few remaining scenes, it removes the scene delay.

The full video is 1:24 and one ended up at this length.

Since then, one has ended up at 1:00 long (so a lot of the last scene delays were skipped), and after clicking export again, the last one is 1:07 - so better, but not 100%.

I changed nothing between the 1:00 and 1:07 export, so it seems to be intermittently deciding how many of the remaining scenes to skip the delay for.

All the transitions are of equal speed, but the scene delays start at 3 seconds and then randomly change to either none (or possibly 1 second).