XIAO BLE with MAX30100 and BLE - arduino

Question

When I run MAX30100 by itself on SEEED XIAO BLE SENSE module everything works fine. But when I add BLE into code, MAX30100 stops getting beats when BLE begins. I am guessing this is to do with pox.update() not updating in time. If someone has any idea what I can do please share. Thank you.
My code is here:
//MAX30100 BPM + SPO2 header
#include <MAX30100_PulseOximeter.h>
//BLE header
#include <Arduino.h>
#include <ArduinoBLE.h>
//Communication header
#include <Wire.h>
//MAX30100
PulseOximeter pox;
uint8_t hearty = 0;
uint8_t oxy = 0;
//MAX timer
unsigned long max_prev_millis = 0;
//BLE timer
unsigned long ble_prev_millis = 0;
void setup() {
// put your setup code here, to run once:
Serial.begin(115200);
if (!pox.begin()) Serial.println(F("MAX30100 error"));
else Serial.println(F("MAX30100 OK!"));
pox.setOnBeatDetectedCallback(onBeatDetected);
// setting the registers for the bluetooth transmit power
uint32_t *TXPOWER = (uint32_t *)0x4000150C;
*TXPOWER &= 0x0;
*TXPOWER |= 0x08;
uint32_t *MODE = (uint32_t *)0x40001510;
*MODE &= 0x0;
*MODE |= 0x05;
BLE.setLocalName("IT'S ME, BLE");
}
void loop() {
// put your main code here, to run repeatedly:
pox.update();
//Heart rate reading every 1 second
if (millis() - max_prev_millis >= 1000){
readMax30100();
}
//Bluetooth upload every 15 seconds
if (millis() - ble_prev_millis >= 15 * 1000) {
BLEUpload();
}
}
void readMax30100(){
hearty = pox.getHeartRate();
oxy = pox.getSpO2();
Serial.print(F("Heart rate:"));
Serial.print(hearty);
Serial.print(F("bpm / SpO2:"));
Serial.print(oxy);
Serial.println(F("%"));
max_prev_millis = millis();
}
void BLEUpload(){
BLE.begin();
BLE.stopAdvertise();
BLEAdvertisingData advData;
advData.setFlags(BLEFlagsBREDRNotSupported | BLEFlagsGeneralDiscoverable);
unsigned char send_data[2]
{
(unsigned char) (hearty),
(unsigned char) (oxy)
};
advData.setAdvertisedServiceData(0x2ACA, send_data, sizeof(send_data));
BLE.setAdvertisingData(advData);
BLE.advertise();
BLE.end();
ble_prev_millis = millis();
}
void onBeatDetected(){
Serial.println(F("Beat!"));
}