I'm having infrequent but recurrent gross hematuria. tests show proteinuria/mucus but no blood. all other tests normal findings. cysto scheduled. ?

Hematuria: Large intermittent blood loss as you describe can often be ascribed by open bleeding tiny blood vessels. This diagnosis would require a kidney angiogram to localize any blood leak, because they can "plug it up" in radiology. Sometimes you never catch it when it starts bleeding. This is called angiodyspasia, not uncommon. Cystoscopy will look for bladder source of bleeding.

Here are some ...: Not infrequently, we have to cope with reality, certainty, & uncertainty after exhausting available means of evaluation for recurrent gross hematuria, but getting urinalysis and performing emergent cystoscopy under local right at the time having gross hematuria will give the best possible chance to document hematuria and know where the blood comes from if professional collaboration be available.