Can't type in default input field until it's hovered over

Partner Rank: 4
Verification Builds: Public 1.7
Summary: Most text input fields don't accept typing input until the cursor hovers over it.
Use Case: Any time you have to type somewhere, it's slow and clunky. You have to mindfully hover your mouse over the creative inventory text box or command block text box before typing.
Repro Steps:
1. Open a command block.
2. Begin typing letters.
3. Hover over the "command" input box with your mouse, then hover off.
4. Continue typing.
Observed Results: Typing does absolutely nothing until the box is hovered over.
Expected Results: Can begin typing immediately after opening UI.
Screenshots/Videos attached: No
Notes:
After a field is selected, other fields can only be activated by clicking, not simply hovering. Essentially, the expected behavior is as follows:

• Default field should be immediately selected when a GUI is opened.
• Clicking should select a different field, hovering alone should do nothing.
• Clicking other buttons should deselect the selected field, with the exception of the creative menu, whose search bar should always be active if it's visible.
  This affects command blocks, anvils, writable books, the creative menu, and game chat. It does not affect signs, which work differently.