Application switching from 10 year partner route to 5 year partner route labeled as " exceptionally complex"

[jane2018]

Hi everyone,

I was recently granted 10 year route in-country leave to remain as a spouse of UK citizen. The reason for 10 and not 5 year route was immigration status as a visitor. (History: we married for many years, lived many years abroad, have children, own house together, bank accounts etc.)

After the grant on 10 year route (2 months later) I applied using 24 hour service for 5 year partner route.
24 hours after attending the centre I received an email from the Home Office stating

"your application raises exceptionally complex issues and we require further time to consider your case thoroughly and reach a decision"

If it is a 5 year route application(after the grant of leave on 10 year route with the same partner), which complex issues can it possible raise?

I thought an applicant can either meet 5 year route requirements or not. (unlike 10 year route application on the basis of Human rights).

Please share some ideas.

[CR001]

It is a standard automated reply. Your application will likely take a bit longer than normal.

[jane2018]

It is a standard automated reply. Your application will likely take a bit longer than normal.

Thank you for the response.

[jane2018]

I feel it is unfair that I was charged extra £600 for super premium 24 hour service but did not get it.

[Alexa1]

Any updates on this? Just to clarify you switched from 2 months of getting FLR (FP) to FLR (M)?
Thanks!