Ever since upgrading to 2.6 I have had problems with prints. Couldn't get prints to stick and even when they did was paper thin honeycomb consistency and the print would just fold when removing.
I went back and printed a calibration cube sliced in 2.4 and had no issues, Sliced a new cube with the same settings in 2.6. Total failure.
I compared the gcode files with software and found very little the same. The main striking thing was the estimate of filament usage. The 2.6 generated gcode was going to use 37.7% less filament. Deleted all my config files, re-imported them and sliced again in 2.6. Same thing. I am back to using 2.4 at this stage as it is producing good gcode.
I am also using Octoprint to deliver the gcode.