Sounds like you have put Scrubfresh on the natural nails before you applied your tips. Next time, apply tips first then apply your Scrubfresh to the natural nails only.
Sorry, How would this cause the tip to crack ?
I mean you apply your scrubfresh to the nail plate, and then wait for it to dry (which is like super quick anyway) Before applying tips, so How could this cause it to crack.
And don't you have to scrubfresh the entire nail plate ?
so surely this would need to be done prior to application of the tip.
Personally It does sound to me like
your tip hasn't been blended enough, so possibly not enough flexibility in the tip, causing the underside to crack..
I have a client who repeatedly had cracks on the tip under the l+p,
She works on computers, (these were white tips by the way which require no blending) and she has them too long imo (although she now lasts 5 weeks without breakages I have to admit, she's doing well lol)
I switched her to sculptured and she is fine now,
I think it was just the constant pressure from the underside of the nail.