Hexacopter stops at 80m and can't fly over 5.5m/s

Hi!
I’ve been flying my hexarotor (frame: F550, BLDC motors: dji 2212/920KV, controller board: APM 2.6, tot weight: 1920grs) and I have some doubts about its behaviour.
I’ve attached two graphs with results of some of the missions I did.
Firstly, in the file called height.png I realised that the hexacopter is stopping at 80m height for a few seconds for no apparent reason. I can’t remember configuring that through Mission Planner. Has someone experienced the same attitude? Something similar happens at 12m height and neither can I explain what is happening.
[attachment=1]height.png[/attachment]
Secondly, in speed.png you can see the average speed of my hexacopter while doing the same missions as in the previous graph. As you can see my multirrotor reaches a climbing speed around 5.5m/s. However, in all three missions I have configured WPNAV_SPEED_UP parameter to be 1000cm/s. At first, I thought I had reached the maximum capacity of my motors, but after checking it, I’ve realised that when ascending, the motors are drawing a total of 45amps from the battery (around 7.5 amps each), which is far from motor absolute maximum ratings. Can anybody help me to understand what might be happening?
[attachment=0]speed.png[/attachment]
Thanks!

I suspect both of these may be bugs that are fixed in 3.2. You really should attach a log file when you’re in the log analysis forum.