PPI of .jpg exporting must translate to 72ppi, is it a bug?

[Higuchi]

Hi there,

I'm facing a trouble about ppi. Through some tests, I found kind of bug about ppi only of .jpg exporting. Even when I designate 36ppi, 150ppi, 300ppi for .jpg exporting, all of .jpg results seem to become 72ppi. This phenomenon seem to occur only in .jpg, not .png, .tiff and .psd. Is it already known bug?

Due to this problem, when I import these renderings on illustrator, the sizes are not same.

Thank you,