The lab says fixation will result in the dyes to leak with the cells. I do think the idea is the fact that fixation might destruction cell membranes. I did find a paper which describes fixation applying methanol or acetic acid, after staining having a DCFDA derivative. DCFDA could be https://lorenzotbgkk.thenerdsblog.com/33587488/the-definitive-guide-to-2-fdck-hcl