Do you have admin right to your system as you mentioned you are not able to see SupportAssist entry under control panel? Under Apps and Features we have to entries one for SupportAssist application and another is for Microsoft Appx (WIN 10 shortcut). In case any driver / software installation get failed that doesn't means SupportAssist will not show any other driver recommendation. When new driver update available for your system then you can see that in SupportAssist but i would recommend you to click on RunAll button instead of running only driver scan. For cross verification you can for driver update perform below steps: once you have both data please share screenshot with me over private message. Accordingly i'll let you know what we can do next.  
 A few days ago support assist offered "OS recovery tools" update. I clicked to update and it failed. Now support assist will no longer scan for other updates. Under "get drivers and downloads" it just says 1 update is available, the only option is "update". when i click update it just lists the "os recovery tools". i've tried several times and it's not goint\g to update that. (i did try someones suggestion to disable antivirus - no joy). Anyway.... I do not need or want the os recovery tools. I just want to remove that failure so support assist will scan for new updates.
support assist no longer checking for updates after a failed update