Tier 2 extension delay - can't start new job?

I'm going to start a new job in October. The Tier 2 visa I'm currently on is going to expire in mid October. I submitted the application to extend it back at the beginning of July, then like many others, made the mistake of opting in the IDV app. Haven't heard anything back after submitting documents through the app on 30 Aug.

Until today I wasn't really worried, since what I understood from the guideline is that I can start my new job before receiving a decision, provided that my application was submitted in time. However HR just told me today that without the decision email they can't offer me a contract beyond mid Oct. I've asked for an escalation but it can take another 10 working days, by which time my current visa will have expired.

Is anyone in a similar situation? Did I or our HR misunderstand anything?

https://www.gov.uk/guidance/coronavirus ... -residents

If you’ve applied for a Tier 2 or 5 visa and are waiting for a decision on your application
You can start work before your visa application has been decided if:

you’ve been assigned a Certificate of Sponsorship (CoS)
you submitted your application before your current visa expired and you show your sponsor evidence of this
the job you start is the same as the one listed on your CoS
If your application is eventually rejected as invalid or refused your sponsor will stop sponsoring you and you must stop working for them.

Thanks, yes I quote that link every time I communicate with the admin/HR. Still they seem unconvinced.

Follow up: HR seems fine with it later. Then I got my application successful email 7 working days after the escalation call.