Hello!
I don't know if it's intended (probably not) but on Julia v1.12, this code:
sys = [tf(1) tf(2); tf(3) tf(4)]
produces:
2×2 Matrix{TransferFunction{Continuous, ControlSystemsBase.SisoRational{Int64}}}:
...
whereas on Julia v1.11 and below the result is:
TransferFunction{Continuous, ControlSystemsBase.SisoRational{Int64}}
...
This is also brings up #975, since a CI test run on the new pre channel would have probably catch this.
edit: just tested using Pkg; Pkg.test("ControlSystemsBase") and yes many tests no longer pass of v1.12