Can confirm the lack of districts and blockers, this mod gives me one Agricultural segment at game start and nothing else. Without this mod I have Agricultural, Industrial and City segments at game start. Also missing are the two new "Ancient Rubble" blockers 3.0 added to Shattered Rings that reduce housing and limits the number of artisan and metallurgist jobs. 3.0 also no longer gives an alloy foundry or civilian industries at game start due to the addition of industrial districts.
The second thing is normal for this mod, the mod spawns a new segment at game start which disappears after a while. In order to build a new segment properly you have to research the various mining techs then start a decision on "The Interloper" to remove it. Once the project finishes there will be a new section in its place that can be repaired just like the other two sections. I have personally verified that this does still work in the new version.

Yes the author updated the mod and the new segment now spawns.
But disticts and blockers are still broken.
I fixed it by replacing lines 378 to 425 of fix_ring_event.txt with lines 1273 to 1424 of 01_start_of_game_effects.txt and removing lines 340 to 357 of fix_ring_event.txt.
Sadly that leaves 5 unemployed specialists, since pops are resettled from the original ringworld and stellaris is weird.

Alright, I just noticed this discussion, what exactly are the problems?

Without your mod a Shattered Ring origin has an agricultural segment, an Industrial segment and a City segment. I also have 5 blockers, three decrepit tunnels, two new Ancient Rubble blockers that were added by 3.0 as well as an administrative office and a research lab.
With your mod I only have one single agricultural segment (and/or an energy district if some variety of machine). The two new Ancient rubble blockers aren't present and I have an alloy foundry and a civilian industries that I shouldn't. Basically the game start is more or less the same as it was in 2.8, which no longer works due to the decreased housing and jobs provided by ring segments in 3.0, giving me 7 unemployed workers and -13 housing at game start.
I think the OPs report about the broken ring segment disappearing might have been referring to the previous version of your mod that they attempted to run on 3.0. Not sure what specifically they are talking about. I checked on a clean install running nothing but this mod and was able to get the ring segment repaired normally.

Yea, fixed the whole ring disaperance bug while updating the mod to 3.0. And, from what I found out while looking vanilla ring over, new ring's starting districts are
1. Nexus, Industrial, Energy and Argiculture for Servants
2. Nexus, Industrial and Energy for Robots
3. Nexus, Industrial and Argiculture for Organics
And there also some difference with blockers, based on either robotic/organic or servitors/everyone else. Also yea, some buildings shouldn't spawn.. I will fix it probably even today.