If I understand you added a print for field 1 and 2 of the current photo and you got a zero for the heigth?
Yes, that is what I did.
Forgot to mention that my OS is Slackware64 and GD is v2.56.
With the '-debug' flag, the output is:
Considering files /home/.../picwoodpecker/2016_11_11_12_50_13_0.jpg
photo data NOT defined for files
filled photo data for current: files
GD Warning: one parameter to a memory allocation multiplication is neg
+ative or zero, failing operation gracefully