Still a problem in the most current release.
I've read on other pages that the issue is with LWJGL and how the release of 2.8.5 saw the removal of support for more than three mouse buttons. The suggestion was to find a copy of version 2.8.4 and replace some files to get support back.
This is still an issue in 1.16.2. Binding the inventory open/close to "enter" still toggles between the inventory and the recipe book if the recipe book is open, instead of closing the inventory entirely. This is particularly frustrating as using the arrow keys and the right hand side of the keyboard generally means that to close the inventory after using the recipe book requires shifting to the far left of the keyboard to use the "esc" key.