I think I finally have the pattern sort of figured out. This is firmware version 1.0.1 on iphone. My app uses 6 super charts. They display 4 traces, 2 traces, 4 traces, 1 trace, 1 trace and 1 trace, respectively.
Since the Blynk 2.0 update (to the one with the Ukranian flag) when the app is launched from the tile, the first two charts come up blank. The others are populated. You must either scroll the superchart, or change the displayed timeframe for it to populate.
Might be a hidden, intermittent bug? For your information.