Hi, some additional results to report. Seems that the buffer char data[] needs to be a bit larger than the given size [130]. It was clipping off part of the JSON payload string in the web hook resulting in several problems at runtime. I am using char data[160] based on the actual size of the payload, and suggest you update this in the example code accordingly.
char data[160]; // See serial output for the actual size in bytes and adjust accordingly.
// Note the escaped double quotes around the value for BLYNK_AUTH_TOKEN.
snprintf(data, sizeof(data),
R"json({"t":"%s","lat":"%f","lon":"%f","spd":%f,"moved":%u,"v10":"%s","v11":"%s","v12":"%s"})json",
BLYNK_AUTH_TOKEN, lat, lon, mph, loc, batt_chg.c_str(), cell_str.c_str(), cell_qual.c_str());
Serial.printlnf("Sending to Blynk: '%s' with size of %u bytes", data, strlen(data));
Was this code tested and running at some point before it was posted to the Community?