When I use r1 mats it shows a concentration cost just fine. However, when using r2 or r3 mats the image below shows the inf concentration cost. This also prevents me from opening the statistics panel to show the concentration cost, doing so freezes my game until I close the window or switch back to r1 mats.

could it be that u are using a missive there that increases recipe difficulty?
is the inf also showing if you do not use a missive?

Same issue here without adding a missive. R1 mats show a ### concentration cost, ranks 2 and 3 show -nan(ind) when simming R4 -> R5; can't sim conc. cost.

Sorry I'm so late getting back to you. It's almost as if the sim knows you can already do it at Rank 5 so it just says -nan(ind) (I believe this is the new message instead of inf) and when you add on a crest and such it doesn't recalculate the cost of concentration possibly? I'm not sure... I've also added on the first example, however, it is a bit different now since I have a higher skill now since last time I reported this.