Don't know why SET LR decisions are slow.
I am one of the August SET LR applicants still waiting. Its nerve wracking when you see most of the August applications have already been decided and HO have moved on to September.
Yes, it makes no sense as I have been on the same visa(Tier 2 ICT) and the same employer throughout my 10 years, so must be straightforward. My previous Tier 2 extension(in Jan 2020) decision came in one day

My wait has entered the fifth month.
The way HO work, I have seen some applications falling through the cracks and it appears I may need to consider myself as one of those unlucky.
I do not see your entry on the timeline thread. When have you applied?