How to reproduce:
1. Create a new project
2. Setup Cache Server or have a valid Remote IP address for the Cache Server
3. Open Preferences window and click Cache Server tab
4. Input a valid asset cache server address to IP Address field, and keep the focus on it
5. Click the "Check Connection" button

Expected result: "IP Address" field updates the text field and then tries to connect to the Cache Server
Actual result: "IP Address" field is not updated, therefore, the "IP Address" field current text value does not matter and "Check Connection" is checking connection with an empty string(the string which was saved with "Enter")

Reproducible with: 2020.1.0a5, 2017.4.27f1, 2018.4.1f1, 2019.1.4f1, 2019.2.0b3
Could not test with: 2019.3 due to "Check Connection" button greyed-out / not working