Have you tested again?
I've seen so many mixed things with the IC. With mine (Accumed - look liked Wondfo), I never had any issues with evaps or anything, but then I've seen so many others that have had lines when they weren't. So hard to say!
Having said that, I tested with an IC the evening of 8 dpo (I was only going to use IC with it being that early), but I definitely had a shadow, so I used a FRER same urine and had a tad bit of a line. It was there for sure, but a super super squinter. I felt like the IC was actually easier to see than the FRER at that point, though the FRER started darkening quicker before the IC.