Some of the MacBook Pro and MacBook Air users are reportedly facing problems with USB 2.0 accessories connected via adapters and hubs. The users have taken to Reddit and Apple Support forums to highlight the problem.
Multiple complaints on Reddit and Apple Forums hint at a macOS bug rather than an isolated case. The users allege that USB 2.0 devices when connected to MacBook Pro and MacBook Air via USB hub stop responding after some time.
When I use an external USB-C hub in any port of my MBP, and connect USB 2.0 devices that include a Filco keyboard and a Razer DeathAdder mouse… after a while (minute or hours) the USB 2.0 devices will stop responding (keyboard dead, mouse not moving or clicking)
The problem persisted even after trying out multiple USB hubs, and unplugging/ inserting back the USB hub. Meanwhile, devices connected to USB 3.0 and USB 3.1 were not affected. Unfortunately, the issue was very difficult to reproduce since it happened randomly. The only noticeable pattern was that issue occurred when two USB devices were connected simultaneously.
Some of the users have used USB hubs from multiple brands and the problem recurred. So this issue has nothing to do with a certain brand/configuration of USB-C. When contacted, Apple asked the user to do SMC Reset, debug in Safe Mode, create a test user and check for the issue, and reinstall the operating system. None of the methods worked.
As a workaround, some users are suggesting using USB hub in their monitor. It is learned that USB 2.0 devices function normally until they freeze. Despite being unresponsive, the device continues to appear in the System Information. In all likelihood, this might be a macOS Catalina concerned with handling and refreshing of USB 2.0 devices.[via Reddit]