I also cannot heal friendly targets either with single target heals either.

Experienced this same thing while trying to do IC dailies. Both times it happened to me, it occurred in the center of the memorial district while trying to place the auricular geodes in the skeletons.

Edit to add: PC-NA, CP Imperial City

@ZOS_Kevin

Please fix it, it makes combat impossible in the imperial city

Sometimes i jump down and people attack me and i cant do anything to them and just die or try to run away

You can fix it by changing districts but it is really annoying

I has this happen to me last night, and nothing I did (reload ui, change zones, roll dodge over and over again) would fix it. As a last resort, I shut down the game and was going to restart it, but decided to update Windows first because I hadn't updated it for a couple of weeks. That ended up taking the rest of the night, so I just went to bed.

In my case, what happened was, I was in Cyrodiil soloing a resource (because I think that was one of the daily endeavors) and everything seemed fine as far as being able to use all of my skills. After I flipped the flag on the resource, I queued for the Imperial City to do the daily Arboretum district quest and craft an item in the Arboretum district for a master writ. I noticed that some of my skills weren't working; the only ones that worked were ones that do damage within an AoE. In addition, the skills which wouldn't work were grayed out as though I weren't within range of being able to hit anything, and all of my skills (even the ones I could use) were completely silent and felt like they weren't making a connection even though they were doing damage as usual. I ported from Imperial City back to Cyrodiil, took the wayshrine to Stormhaven to turn in my master writ, and tried fighting some assassin beetles near the writ dropoff location. As was the case in Imperial City, most of my skills were grayed out as though I was out of range, and only my AoE attacks would work.