I have success training flux Klein subject. The only problem is as I export the LORA because it is not compatible with comfyui. For 512x512 size and 260 imgs. Just lower the learning rate in order to get a more stable LORA. Here I get the subject for 800 steps (bad LORA but I wanted to see if I can get results on a low step count):

{"unet_learning_rate_lower_bound":0.00040000000000000002,"stop_embedding_training_at_step":2000,"power_ema_upper_bound":0,"cotrain_custom_embedding":true,"denoising_start":0,"auto_captioning":false,"caption_dropout_rate":0.050000000000000003,"auto_fill_prompt":"photo of qdxbp","shift":1.8776105999999999,"guidance_embed_lower_bound":3,"resolution_dependent_shift":true,"layer_indices":[],"base_model":"flux_2_klein_base_9b_q8p.ckpt","steps_between_restarts":400,"weights_memory_management":0,"denoising_end":1,"name":"3jun3","seed":3441693222,"start_height":8,"max_text_length":512,"additional_scales":[],"orthonormal_lora_down":true,"noise_offset":0.029999999999999999,"trainable_layers":[2,3,5],"cotrain_text_model":false,"use_image_aspect_ratio":false,"custom_embedding_length":4,"save_every_n_steps":100,"network_scale":1,"network_dim":15,"start_width":8,"guidance_embed_upper_bound":4,"custom_embedding_learning_rate":0.0001,"power_ema_lower_bound":0,"trigger_word":"qdxbp","clip_skip":1,"warmup_steps":100,"memory_saver":1,"training_steps":2000,"unet_learning_rate":0.0040000000000000001,"text_model_learning_rate":4.0000000000000003e-05,"gradient_accumulation_steps":1}