#include "SparkFun_Qwiic_OpenLog_Arduino_Library.h" //I2C SD card data logger
You are including the library for the i2c version of the open logger. Is that what you are using?
Your sketch with the myLog.print() is using the syntax of the Serial version of the open logger. The syntax for the i2c version is .write() for a single char and .writeString() for multi bytes, but must be less than 31 in the line.
You say that everything worked properly until you added the
web page and the oled so perhaps you do have the Serial version. But then again I would think that with the mkr1000 you would have the serial version connected to Serial1.
Please clarify what Open Log you are using, and how it is connected to the Arduino.