Immediate P60's

I run payroll for many of my clients. As I am running most of this month's payrolls early due to clients wanting the furlough payment in the bank before they have to pay out the wages at the end of the month, I have assumed that as M12 is included on the YTD figures on the payslip that I could run the P60's (which I have done for a few). It wasn't until I had produced a P60 for a one director company who hadn't been on furlough that his gross figure on his P60 wasn't £12,500 it was a month shy. On contacting Kashflow I was told that the P60 wouldn't be updated until the FPS is submittted. As you can't restore M12 surely it would be better that everything can be done at the same time.