UB are really slow form my experience. I applied to switch to UB on Feb 2nd, got final approval on April 10th, so 9 weeks. I didn't even get AIP from them for this application.
Between first submitting all the details, the advisor was out sick for almost 2 weeks and didnt have their out of office or provide any other contact point, the application was then not uploaded correctly so underwriters were also emailing the advisor asking for it to be re-uploaded. They also got no reply from advisor on their side, meaning more delay.
Once that was sorted, the valuation team were over a week organising a valuer despite the valuer saying he was emailing asking for work etc etc. I emailed **15 times** over the 9 weeks asking what was happening and asking to be kept up to date, as I had no idea what was happening.
Contrast this with BOI/PTSB where I had previously full offer in less than 4 weeks. Hence, I wouldn't be worried that its a bad sign, my experience is that they are just slow in general.