My HDX900 has zebra 1 set for 70%, zebras come in at the correct 70 IRE, however, they everything above 70 IRE also has zebras. Zebra 2 is off. I normally have it set to 100%, but I'm not getting the different zebra pattern and because everything above 70 IRE has zebras
anyway, they overlap.
Zebra set only has one level, that at which the zebra's appear. They do not have an upper "limit" so that any thing above your 70% setting will show zebra. This is proper, and the reason why I, and many others, set our zebra setting to 98 or 100, so that we essentially use the indicator as a warning of impending clip and overexposure.