Cool, thank you. I'm more reporting the other scenario where SI is not being calculated correctly to make sure it's fixed as well. I've only read folks talking about replacing the lowest block not updating the SI and want to make sure the devs catch and fix this permutation. Plus it gives them an easy repro to test their fix with. The other easy repro is a Y type shape that you convert to an H shape.
Luckily most folks who are server maintainers and/or playing single player already knew about how to fix it as it shows it right in the UI that you use to look at SI. Well at least it was obvious to me. LOL But great you were able to share the fix with those who didn't realize how to do so.
Also your fix will only work for folks who have access to do so, those who play on servers may not have that luxury, so until then if they upgrade the lowest supporting block it'll update the SI above it for that pillar.