As said in the summary, I can't toggle off sprinting while I'm in a sprinting mode. It can be done only after I completely stop moving. There is not such a issue with shifting (crouching). That can be toggled or toggled off anytime. 
**If I could recommend an improvement (besides of actually fixing the bug), maybe you should also add some kind of visual notification when crouching or sprinting mode is toggled.

Thanks