In order to reproduce the issue we sent information to all the affected users who have either voted or commented on this thread.
Based on the replies we got we could infer that the issue is occurring when a third party software or application is also running in parallel. Some examples of the software used include Global Auto-correct, Google Chrome,
Moreover, when the issue occurs it seems to hamper all CC applications such as Illustrator, InDesign and Photoshop.
A possible fix for the solution includes restarting the application or restarting the system.
In the absence of any consistent reproducible steps, we are currently closing this thread as “not reproducible”. In case you again encounter the issue, please create a new thread mentioning the steps with which we can reproduce the issue and additional softwares, if in case any, that you are using.
InDesign TeamDoug commented
If I shut down safari "spacebar shortcut" works, and continues to work after restarting safari. Until it happens again later. Hope this Helps