Weird problem with DELETE key

I've got a very strange problem with the keyboard DELETE key in my Windows 11 system-- it works correctly in some situations, but not in others. Here's what I mean: the system responds properly to the DEL key in situations like CTRL-ALT-DEL, or tapping the DEL key while booting to get into the BIOS. However, the DEL key won't work for its normal function: it won't delete text in a text editor or word processor, it won't delete a highlighted file in File Explorer, etc. etc. etc. I've tried this on many different applications, but it's always the same thing- when I press it, nothing happens at all.

The problem is definitely NOT with the actual keyboard itself, but somewhere in the system, because I've swapped out two keyboards and the same problem occurs with both of them. The driver is allegedly up to date, and I've tried uninstalling the keyboard through Device Manager, then rebooting, no improvement.

Does anyone have an idea what else I can try?

System: Windows 11, AMD Ryzen 9 7950X CPU, 32 GB Corsair Vengeance DDR5-5600 RAM, Corsair RM850X PSU, MSI MagB650 Tomahawk WiFi Gaming Motherboard, Asus DUAL OC GeForce RTX 4070 Ti SUPER GPU.