How to reproduce:
1. Open the attached '1296815.zip' project
2. In the top menu bar select Custom > First Test
3. Scroll down to the bottom of the First Test window
4. Observe the First Test window

Expected result: Every entry contains a dropdown next to the entry title
Actual result: Some entries don't contain dropdown

Reproducible with: 2019.4.16f1, 2020.1.17f1, 2020.2.0f1, 2021.1.0a9
Cannot test with: 2018.4.30f1 (due to errors)

Notes:
- The EnumField dropdown is still clickable
- The max element number seems to be inconsistent (e.g. sometimes the elements aren't drawn correctly when the list contains 140 elements, however, after changing this number to 139, refreshing the page, then changing the number back to 140 and once again refreshing the page results in the elements being drawn correctly)
- Tested with the built-in UI Toolkit version, because the newer versions cause errors