Arduino USB serial connection to Raspberry Pi (Rasbian) not initializing - arduino

Question

I have an Arduino Nano 33 iot that outputs data via Serial at 38400 baud, connected via USB. Setup starts with Serial.Begin. The Raspberry Pi 4, running Raspian buster is set up to receive the data. It can see the correct port, /dev/ttyACM0, but nothing comes in.
I even installed the correct Arduino IDE and SAMD board package on the Raspberry Pi. It still does not find it until after the IDE uploads the replacement sketch and the CPU is reset. The IDE can grab the serial number and board type though. I can then exit out of the IDE and the Arduino is still pumping out serial to the Raspberry Pi.
The only other way to make it work is by pressing the reset button on the Arduino every time a reboot is done on the Raspberry Pi. Serial was tested on the Pi using screen.
Neither of these options are convenient. What am I missing?
/*
Connects via I2C to a CMPS14, outputs NMEA0183 HDM sentences via Serial (38400 baud)
By James Henderson, 2014, adapted to output NMEA sentences by Ian Van Schaick
*/
#include <Keyboard.h>
#include <Wire.h>
#define CMPS14_ADDRESS 0x60 // Address of CMPS14 shifted right one bit for arduino wire library
#define ANGLE_8 1 // Register to read 8bit angle from
unsigned char high_byte, low_byte, angle8;
signed char pitch, roll;
float angle16;
int fine;
float bearingH; // Holds whole degrees of bearing
float bearingL; // Holds decimal digits of bearing
int bearing;
char nbsp;
char mystring[25];
char mystring2[25];
char mystring3[25];
int software;
int cal;
unsigned int _last_status;
uint8_t checksum(char *s)
{
uint8_t c = 0;
while (*s)
c ^= *s++;
return c;
}
void CMPS14_eraseProfil()
{
Wire.beginTransmission(CMPS14_ADDRESS);
Wire.write(0x00);
Wire.write(0xE0);
_last_status = Wire.endTransmission();
delay(20); // 20ms delay after each of the three bytes send
Wire.beginTransmission(CMPS14_ADDRESS);
Wire.write(0x00);
Wire.write(0xE5);
_last_status = Wire.endTransmission();
delay(20); // 20ms delay after each of the three bytes send
Wire.beginTransmission(CMPS14_ADDRESS);
Wire.write(0x00);
Wire.write(0xE2);
_last_status = Wire.endTransmission();
delay(20); // 20ms delay after each of the three bytes send
}
//Correct heading for known deviation
int DeviationCorrect(int Head)
{
return 0;
}
void setup() {
Serial.begin(38400); // Start serial port
Wire.begin();
nbsp = 32;
// CMPS14_eraseProfil();
}
void loop() {
Wire.beginTransmission(CMPS14_ADDRESS); //starts communication with CMPS14
Wire.write(ANGLE_8); //Sends the register we wish to start reading from
Wire.endTransmission();
// Request 5 bytes from the CMPS14
// this will give us the 8 bit bearing,
// both bytes of the 16 bit bearing, pitch and roll
Wire.requestFrom(CMPS14_ADDRESS, 26);
while (Wire.available() < 26); // Wait for all bytes to come back
// software = Wire.read();
// Serial.print("Version: ");
// Serial.println(software);
angle8 = Wire.read(); // Read back the 5 bytes
high_byte = Wire.read();
low_byte = Wire.read();
pitch = Wire.read();
roll = Wire.read();
// int i = 6;
// while (i <= 25) {
// Wire.read();
// i++;
// }
//
// cal = Wire.read();
// Serial.print("Cal: ");
// Serial.println(cal);
bearing = ((high_byte << 8) + low_byte) / 10;
fine = ((high_byte << 8) + low_byte) % 10;
byte data[128] = "$HCHDM,";
data[8] = bearing;
// int deviation = 0;
//DeviationCorrect(bearing);
// bearing = bearing;
//+ deviation;
//Print out NMEA 0183 string HDM
snprintf(mystring, sizeof(mystring), "$HCHDM,%d.%d,M", bearing , fine);
uint8_t crc = checksum(mystring + 1);
Serial.print(mystring);
Serial.print("*");
if (crc < 16) Serial.print("0");
Serial.println(crc, HEX);
//Print out NMEA 0183 string XDR for Pitch
snprintf(mystring2, sizeof(mystring2), "$HCXDR,A,%d,D,PITCH", pitch);
uint8_t crc2 = checksum(mystring2 + 1);
Serial.print(mystring2);
Serial.print("*");
if(crc2 < 16) Serial.print("0");
Serial.println(crc2, HEX);
//Print out NMEA 0183 string XDR for Roll/Heel
snprintf(mystring3, sizeof(mystring3), "$HCXDR,A,%d,D,ROLL", roll);
uint8_t crc3 = checksum(mystring3 + 1);
Serial.print(mystring3);
Serial.print("*");
if(crc3 < 16) Serial.print("0");
Serial.println(crc3, HEX);
delay(100);
}