Steps to reproduce the issue:
1. Download and open attached project.
2. Open scene named "scene01".
3. Enter the Play mode.
4. Notice that one UI particle object was instantiated and "ATK Dice" text object appeared in the "Game" window automatically.
4. Try pressing Space bar every second (or even more frequently) for some time to instantiate more UI prefab objects.

Actual result:
Sometimes UI prefab objects are not displayed on the screen, yet they are instantiated, since "Spawned" counter registers them and they appear in the "Hierarchy" window.

Expected result:
Every instantiated UI prefab object should be displayed on the screen.

Reproduced with:
5.4.0f3, 5.5.0a5.

Cannot reproduce with:
5.1.5f1, 5.2.5f1, 5.3.6p2.