Automatically logging off a user after 30 minutes of inactivity is not an option but an IRS requirement for all tax software developers, including Intuit, that came out of the 2016 Security Summit.  There is no option for turning this on or off.

Do you have a mouse jiggler of some sort installed?  Or perhaps you were on the PS screen on and off?

If you still have problems with that, you should contact Intuit Support so that they can look into that for you.