Montage Section Links Don't Update When Section Deleted

Hi there, I noticed that there is a problem with Montage Section links not updating when a section is deleted from a montage asset.

We had a montage with a "Default" section and a "Loop" section. They were linked so Default -> Loop.

We deleted the "Loop" section from the montage. But the NextSectionName for "Default" was still set to be "Loop".

This doesn't affect client playback but we found it as we simulate montage playback on the server using metadata which contains the CompositeSections data from UAnimMontage. Our simulation then tried to jump to the "Loop" section even though it did not exist anymore.

In the Montage Asset Editor, in the Montage Sections window, if we click on the box to add new section link for the "Default" section, we have the option to "Remove Link" which is only available when there is a linked section. I've attached an image of that for clarity.

Steps to Reproduce

Open the 5.3.2 editor

• Make a new montage asset
• Add a section called "Default"
• Add section called "Loop"
• Add "Loop" as the next section to play after "Default" in the Montage Sections window
• Delete "Loop" section from the montage asset
• Observe that in the CompositeSections data on UAnimMontage, the NextSectionName is still set to "Loop". The "Remove Link" option will also be visible in the Montage Sections window if you click to link "Default" to a new section