I have found Google Chrome will sometimes "steal" the ability to type or use your keyboard if you have a Google product open (like Sheets, Gmail, GoogleDocs, etc). Try closing Chrome and opening it up again and seeing if your keyboard inputs respond in all your other apps again.

Corey Key , Govind Gupta , everyone who's responded:
It IS a RAM issue. When I replaced my computer with one with much more RAM, the issue disappeared. Hand tool stuck was one manifestation, or maybe illusion, of software performing hyper-slowly. I guess a string of commands getting stuck together would look like the hand tool was running amok.

My issue is resolved. Answer: MORE RAM.

Thank you all for your help! And Corey Key , you were correct!

I had the same issues in both Photoshop and Illustrator. It started happening after I installed Duet Display (a third-party app that supports an iPad as a 2nd display) on my 2018 MacBook Pro. I tried all the fixes mentioned here and nothing worked. Finally uninstalled Duet Display and I'm back in business. Maybe it's a RAM issue with Duet Display or third-party conflict. Thought this might help.

Same problem here. Spacebar just stopped working. Today is 15/April/2019. Sad...

This happens to me on and off and really disrupts my workflow. I wasn't able to accomplish nearly as much yesterday as I was hoping to. Quitting/restarting chrome does nothing to fix the issue - it sometimes resolves on its own but always comes back to haunt me at unexpected times. Please fix!

Following as I am experiencing the same issue. Come on Adobe.

so when will we receive an update? this is making things more time consuming? we need this a=back asap please

My hand tool and other functions are working now: solution? A computer with MORE RAM. Maybe it should have been obvious to me, but I’d been using the same computer for many years. Perhaps the software grew with updates. I wonder why no one thought it would malfunction with lack of space in which to work?

Anyway I know that now.

Illustrator needs lots of RAM.

Thanks all who tried to help.

Same as well! Just today. So annoying! I quit illustrator and updated it, to be safe, re-opened and same problem! The only fix was, thankfully in the thread here, when someone mentioned clicking the mouse outside of the program and clicking back.

This once again proves the flaw of Adobe beta testing methodology. Meaning they need real-world beta testing because the would have been caught almost immediately before public release. Reading the comments by engineers is not very encouraging. This is basic work flow 101 for Ai. Losing it doesn't seem huge until you lose it and it immediately becomes a pain. This also seems to be happening in Photoshop too so the problem is systemic in that regard. Originally posted in 2017 yet still happening in 2019 only shows how lethargic their attention to detail is regarding development. I won't hold my breath.

Still having issues with this. This is such a useful tool and it's truly an inconvenience.
I hope you fix it soon.

I fixed this issue my using a mouse instead of my laptop key pad. nothing to do with chrome etc

Fix this immediately please. You are disrupting my workflow!! "Stop moving my cheese
Adobe!

I don't have Safari or Chrome open and spacebar still won't work as quick hand tool. This is killing my productivity.

SAME PROBLEM! Really annoying. Thankfully quitting and restarting Google Chrome fixes it, BUT only temporarily, as I have to do that once or twice a day.

PLEASE fix this, Adobe. It seems that ever since Adobe started prescription-apps, the problems have increased and persisted longer. >:(

same issue!! have had it on multiple computers and both CS6 and CC

Me, too, I updated my Illustrator just now, too... Its super annoying, I deleted Plist and Adobe Prefs before still didn't work

Restarting Chrome always solves this problem, but it happens a lot.

This happened to me and I restarted my computer and now it works.

Having the same issue and it's incredibly irritating. Please sort it out and get me back my quick hand tool.