Could you post some details about both the host Mac and the virtual machine (LInux/Windows, what version), as well as details about what types of keyboard/mouse are you trying to connect.
"It was not like this yesterday" has me asking the question: did anything change between when it worked and when it didn't? For example, updates to the host Mac or updates to the VM's operating system.
My first thought is that the devices are getting claimed by macOS as HID-type devices and Fusion is virtualizing them as it does the system keyboard/mouse as the virtual keyboard/mouse it presents to the VM. As an example, I connected a USB mouse to my Mac that has Bluetooth keyboard and mouse, and the device isn't seen in the Fusion USB menus as a device that can be attached. Yet the mouse does work in the VM the same as my primary mouse.