Dupes are unresponsive about sweeping up

For sweeping, dupes need to have containers that can hold the item and has enough free space. Make sure you have enough storage compactors or ration boxes/freezers when you want to sweep, and make sure they're accessible to them (use Show Navigation option on the dupe to check places he can access). Some materials cannot be swept, such as solid gases or phosphorite.

It is possible to set up priority for sweeping/mopping: when you select the Sweep or Mop tool, there is list of priorities 1-9 right below the tool icons. Any action planned this way will be planned with the selected priority.

Also, when the game starts behaving weird, save your progress and restart the game, then try again. That helps avoiding problems caused by general instability of the game (note it's Alpha) and helps check if the problem is reproducible.