Hello!
Thanks for registering and reporting the issue!
I've tried but unable to reproduce it. We have not received other similar reports either which is strange as the item usage and medicine cooldown system were implemented months ago.
As you've mentioned, the issue happens only "sometimes". Could you provide the steps that are most often result in the issue, please? Are there any details (such as "usually the issue happens I'm driving a hoverboard").
Or maybe you can provide a captured video—that would be most helpful!
Some notes: the medical cooldown doesn't allow using more medicine or firing weapons immediately after using the medicine. For some medical items, the cooldown may take up to 10 seconds. Though you can switch the currently selected item freely—and as soon as the cooldown expired you can use it. Could it be the problem that you're describing, or maybe the issue is linked to it?
Regards!