Sion's Q and R won't work after using ult at the same time while dying

This is a speculation, but the bug is still there. Like the title said, I can't use Q or R on Sion after dying after using ult right when I die. The ult goes of, but when I revive I can't use my Q or ult any more. This happened to me twice, I tried rebinding my spells, reconnecting, and clicking on the spells instead but it doesn't work. My keyboard works perfectly. But I was lagging both times this bug happened to me, so maybe it's a combination of me lagging while using ult right when I die.