I've encountered a bug where I can run and walk but can't jump while doing so. If I'm not moving I can jump. I've ruled out encumbrance by trying this with empty bags. How can I fix this?
I'm playing Skyrim - Legendary Edition on Windows 7.
You could try entering and exiting sneak mode and also check under the Magic-tab if your character has any illnesses. That's what these sources of people with similar problems suggest, but they complain about not being able to jump at all:
Also, if you have one you could try loading an older save and see if it still works there.
(I would have commented this, but unfortunately I lack the reputation.)
This is the same on my keyboard and I heard that Logitech (for my point) blocket this by their driver, because they want to sell their expensive gaming keyboards. I could imagine, that other companies do the same. You cannot press Ctrl + W + Space at the same time (well you can, but it doesn't do what you want).
I hate stuff like this, because they did extra work to cut the opportunities you'd have. You can maybe change the keys for this actions, but I don't know if this helps.