Bug in v8.5 multigraph?

Im using energy metering with EMONCMS 8.5. inputs and feeds are working as expected, but I found some strange behavior os system. I have daily energy consumption calculated by two independent ways and I have two bagraphs, one for each calculation method. Both work fine. But when I want to compare them putting these two daily bargraphs into one multigraph, there are somehow messy results. Some days have no bars, some have bars with unreal values. The same happens, when I combine for example rawdata of outdoor temperature (curve) with bars with daily minimal/maximal value (bars). Line is OK, but bars are messed like in above with two bargraphs of energy consumption. Simply, when you create multigraph with daily bargraph values, something is wrong with their presetation. Any idea how to solve this?

Radek