Power problems (Brown out?) on every flight

I appear to be having power problems - looking like a brownout on every flight with IRIS.
In particular I’m experiencing the issue described here: copter.ardupilot.com/wiki/common … wnOuts_etc, where the BarAlt reading stops at multiple meters above ground.

Also the end (with varying length) of each flight appears to be missing in each log. The landing - which I either conducted in Stabilize mode or RTL mode is missing from each of the flights attached below.

On the first flight IRIS went into Battery Failsafe and landed itself, which was also not recorded. Other than that I didn’t have any noticeable issues during these flights.

Any ideas what could be the issue here? Thanks!

This behavior seems to be caused by incomplete log files and is not an actual brownout: