Well there is a beta version 17.1.2286 and there is the regular release 17.1.2286 (confusing). If you took part in the beta testing you need to check you have the latest (build 17.1.3394).
I ran a Smart Scan but nothing was found, so no Details button for me.
Clicked the Notifications bell, which has a Details button (presumably this is what you are talking about). I can click that details button till the cows come home and no details (presumably because nothing was found) and no restart of the Smart Scan.
I have avast 17.12286 build 17.1.33940
And once the smart scan has finished and click on the bell notification details
it will start to run the scan again.
This part is a bit glitchy sometimes. It’s not end of the world and I believe they are working on it. It just didn’t land in the release version. Some extra glitches will be resolved during this week and in the next monthly update in March.