What is the "gap" and how do I eliminate it?

I have an MSIX installed via App Installer. I've got it working, but sometimes after an update there is a very long pause before the app is relaunched.

In the Event Viewer there is a helpful breakdown of where the time during an install/upgrade operation is spent. Unfortunately almost all the time is allocated to something simply called "Gap", strongly implying that during this pause the App Installer is in fact doing ... nothing. Example:

1. Performance summary of Deployment Add operation on Package DemoApp_3.10.0.0_x64__49jahnq5qzr1m:
2. Overall time: 32875 ms
3. Enqueue cost: 359 ms
4. Dequeue delay: 0 ms
5. Bundle processing cost: 0 ms
6. Indexing cost: 16 ms
7. Resolve dependency cost: 16 ms
8. Check approval cost: 125 ms
9. Evaluation cost: 187 ms
10. Hardlinking evaluation cost: 31 ms
11. Stage required cost: 500 ms
12. Flushing and closing files cost: 0 ms
13. Machine register cost: 0 ms
14. Stage user data cost: 0 ms
15. Gap: 31453 ms
16. Registration cost: 47 ms
17. Gap: 31 ms
18. Repository commit transaction cost: 79 ms
19. Gap: 46 ms
20. Data flush cost: 16 ms
21. Post DeStage repository commit transaction cost: 0 ms
22. Remaining cost: 0 ms

This is rather puzzling, to say the least. Most of the categories are self explanatory, but can any MSIX experts explain why there is an apparently pointless 31.4 second pause after "Stage user data" and "Registration"? And, does anyone know how I can get rid of this "gap"?