When the Mosaic tool offers to delete existing jobs, it may incorrectly remove its own new jobs.
Evaluation occurs at each job insertion, so new jobs may be reordered in the middle of existing jobs.
Therefore, if requested to remove existing jobs, do this before adding mosaic jobs, not after.

Create and add a scheduler job, then open the Mosaic Tool.
Configure the Mosaic Tool, request it to create the new jobs.
When asked whether to keep existing jobs, select "No".

Repeat the test with:

• No scheduler job selected
• The new scheduler job selected
• Option "Reorder jobs per altitude and priority" enabled

Without the change, some new jobs may be deleted and not make it in the final list, while old ones may be kept.
With the change, existing jobs are properly removed before adding new ones.