I've always used Kohya-SS for training Illustrious LoRAs because the results are WAY better than AI-Toolkit's, while also being cheaper to run on Buzz for similar results.
However, it seems like something has changed in Kohya-SS, because now I can't train LoRAs with more than 20 steps or use resolutions higher than 1024.
You can try, but I think you'll run into the same error: "Error computing cost - Your request is invalid."
It seems like the system is applying AI-Toolkit's 20-step limit even when using Kohya-SS, which should support higher step counts.
And unlike AI-Toolkit, you can’t even use “Train Further” in batches of 20 steps. This leaves you stuck at step 20, making it impossible to achieve decent results with complex characters and outfits, which typically require around steps 23–27 for my LoRAs.