1) Had to fix severe bugs in a dynamic UI (configuration-driven forms) component.

Recognized undocumented Copy/Paste/Modify/FuckUp driven variations of the same component all over the project. Unsurprisingly, the implementations covered 99% of the antipattern catalog on wiki.c2.com and could compete with brainfuck in regard to human-readable code.

Escalated the issue, proposed a redesign using a new approach, got it approved.

Designed, Implemented, tested and verified the new shared and generic component. Integrated into the main product in the experimental branch. Presented to tech lead/management. Everyone was happy and my solution opened even more possibilities.

Now the WTF moment: the product with the updated dynamic UI solution never has been completely tested by a QA engineer despite my multiple requests and reminders.

It never got merged into baseline.
New initiatives to fix the dynamic UI issues have been made by other developers. Basically looking up my implementation. Removing parts they do not understand and wondering why the data validation does not work. And of course taking the credit.

2) back in 2013, boss wanted me to optimize batch processing performance in the product I developed. Profiling proved that the bottleneck ist not my code, but the "core" I had to use and which I must never ever touch. Reported back to him. He said he does not care and the processing has to get faster. And I must not touch the "core".

(FYI: the "core" was auto-generated from VB6 to VB.Net. Stored in SourceSafe. Unmaintainable, distributed about a bunch of 5000+ LoC files, eye-cancer inducing singlethreaded something, which had naive raw database queries causing the low performance.)