Bare 328p verification mismatch thru IDE, not with AVRDUDE

Í'm getting verification mismatches when uploading from the Arduino GUI (1.6.12) but uploading from the command line with AVRDUDE runs flawless (on the same .hex file).

  • Programmer: Tinyloadr (usbtiny compatible)
  • ATmega328p loaded on the programmer (it as a zif socket). Project connected with wires from breadboard
  • Using James Sleeman's libraries for mega8/168/328 etc
  • ATmega8 programming runs withour error from the gui (due to RAM size, I am not able to use this one for my project)
  • ATmega328p gives verification errors (first mismatch at byte 0x0100 0x56 != 0x5e)
  • Running AVRdude with the -e parameter runs without error

Now I read an awful lot about the Arduino parameters and I tried to change them in the PROGRAMMERS.TXT file:

usbtinyisp.name=DIY ATmega: USBtinyISP
usbtinyisp.protocol=usbtiny
usbtinyisp.program.tool=avrdude
usbtinyisp.program.extra_params=-e

I even found PROGRAMMERS.TXT in a personal tree:

C:\Users\[user]\AppData\Local\Arduino15\packages\diy_atmega8_series\hardware\avr\2016.7.21

Are there any other options to try?