Acro Package support is broken
The support for the acronym package acro
was added 5 years ago in 1cd0b81a and wasn't changed from then on. But it is mentioned in the manual.
In version 3 of acro
(released in 2020), the styling commands changed completely. So the ones currently in use in ifiseries.sty
don't work anymore. So if I try to use this style together with acro
and a somewhat recent tex distribution, my document won't compile anymore.
I think the easiest fix is to force the use of acro
version 2 by changing line 280 in ifiseries.sty
to \RequirePackage{acro}[=v2]%
.