Illustrator 2020: How to have Pantone with integral CMYK values (Legacy)? Was working in 2019

I work in flexography printing, we're making flexo plates. Most of the time, like on 90% of the jobs, we receive files that have too many pantone colors. So, let's say, a printer can only print 8 colours on his press, we need to convert some Pantones into CMYK. But I need the Pantone with whole and accurate numbers. Before, I was able to just use the "Use CMYK values from the manufacturer's process books" option from "Spot Colors Option".

Now, on Illustrator 2020, it doen't work. It was useful because sometimes clients come back later and ask us to make the 485 in Pantone and convert an other color to stay under the 8 colours limit. It was easy to revert with one click and convert the other one with one click.

Because in our field, you want to print a Pantone 485 with 95% magenta and 100% yellow. Printing a 485 with 7.92% cyan, 97.1 magenta, 100 Yellow and 0.83% of black won't work.