Disclarimer: sorry for the wall of text and for my English: I tried to describe the problem as best as I could and English is not my native language.
Hello. I have a following problem with my Shimano 105 R7000 new (4k KM) rear shifter:
At the end of a ride a week ago something happened inside it and it stopped shifting altogether all of a sudden. The feeling was as if something disconnected/snapped. I took the bike to my LBS, where the cable was replaced. However, the shifting is not the same anymore. It is impossible to adjust the shifting so that both of the following work: big chainring + smallest sprocket and small chainring + biggest sprocket. The shifting is also clunky no matter what. The chain will always rub against the next sprocket before shiting to a bigger one and will often slam into smaller one. Regardless of how much I fiddle with the barrel adjuster. Also, shifting from 6 to 7 or 7 to 8 smallest sprocket requires two clicks of the lever and a downshift afterwards. Else it won't shift - the derailleur IS moving, but doesn't go enough of a distance to facilitate a shift. Most it gets is a rub on the next bigger sprocket. Conversely, shifting to smaller sprocket afterwards won't produce a shift after 1 click, but instead will shift 2 gears after two clicks (so then to back one gear I have to do the previous routine again).
Needless to say this is hell. The problem is that I had exactly all of these symptoms 8 months ago. Exact same scenario resulting in same symptoms happened to me in November when I hit first snow in Sweden. Back then, the problem got eventually solved by getting a new shifter (after lots and lots of unsuccessful troubleshooting). So now, apart from wanting to fix the problem, I really want to know what is this.
To add to the description: both times, the shiter looks and feels differently than before the incident. The lever is angled a bit more towards the frame. The braking aspect of the lever is now different as well: the distance from the lever's resting point to the "max brake applied" point is around 6 mm shorter. I noticed this as soon as I first got on the bike (I'm quite sensitive with my brakes).
Here are the photos where the shifter's angle as well as the brake distance capacity is visible: https://i.stack.imgur.com/3phKK.jpg
I think it is also worth to add that I have a new casette (2500 KM) and a relatively fresh chain (1000 KM) ridden in good weather conditions. They are both well lubed. The shifter is also lubed. The cable end bit sits correctly in the designated slot in the shifter. The rear derailleur seems to be fine too and shouldn't have been touched or affected in any way, but I have made photos as well: https://i.stack.imgur.com/q44uh.jpg