Solved No checks beside Win Updates after Win 8.1 Repair Install

I just repaired Windows 8.1 Pro (64bit) following the instructions in "How to Repair Install Windows 8 and 8.1 without Losing Anything". I did this because I kept getting DISM Error: 0x800f0906 ('The source file could not be downloaded') despite trying all the suggested solutions I could find. The repair was successful and DISM is repaired.

I have Windows Update set up to "Check for updates but less me choose whether to download and install them". Prior to this latest repair, when I clicked View Details, there was always a check mark beside the updates which I could uncheck if I didn't want to download any particular update. After this repair, there is a huge list of updates in Windows Updates (176 Important and 8 optional) but there are no check marks beside any of them.

Does this mean that the Windows ISO file I downloaded and updated from Microsoft at Create installation media for Windows 8.1 - Windows Help already incorporated these updates? Or do I have to install all the ones I deem to be important and necessary? The files total 2,609.0 MB. For security reasons, I want to be sure that all truly important updates are installed. OTOH, if they are already incorporated in the Windows ISO file created from the download, I obviously want to avoid that step. Any help and/or explanations would be greatly appreciated.

After cleaning up some unwanted updates re Win 10, the check marks were restored and, after checking installed updates in Control Panel, I realized that I had no choice but to install all the Security and necessary important updates.