How to reproduce:
1. Open user-submitted project (Project.zip)
2. Open the 'new input action' asset
3. Make sure that "All Control Schemes" is selected
4. Select any action(e.g. Fire/Left Button [Mouse])
5. In the properties tab to the right, click the 'Path' button

Expected result: the list of devices is displayed and the 'Listen' button detects individual device input
Actual result: the list of devices is not displayed and the 'Listen' button does not detect any individual device input

Reproducible with: 2019.4.6f1, 2020.1.0f1, 2020.2.0a20(Input System preview.7 - 1.0.0, 1.0.0)
Not reproducible with: 2019.4.6f1, 2020.1.0f1, 2020.2.0a20(Input System preview.6 - 1.0.0)
Could not test with: 2018.4.26f1(Input System 0.2.1 - preview - All Control Schemes option unavailable)

Notes:
Only affects "All Control Schemes"; selecting a single Control Scheme does not cause this issue