How to reproduce:
1. Open the attached "Repro Project" and open the "Sample Scene"
2. In the hierarchy select the "1" object and observe its array
3. Now multi-select "1" and "2" objects and observe the array again

Expected result: arrays with high element counts (>64) are not displayed when multi selecting to avoid performance issues (A message explaining this used to be shown)
Actual result: arrays with high element counts (>64) are not displayed when multi selecting and show up as "empty"

Reproduced in: 2021.2.0a6, 2021.2.0a5
Not reproducible in: 2021.2.0a4, 2021.1.0b8, 2020.2.6f1

Note: Adding [NonReorderable] fixes the issue indicating that this is a ReorderableList only problem