Non blocking read not working

[albfan]

I just found on this tutorial:

http://kstobbe.dk/2019/02/16/esp32-pms5003-bme280-mics6814-sensor-build/

using blocking read:

  if (pms.readUntil(data, 2*PMS::SINGLE_RESPONSE_TIME))

and this effectively allow me to read data from PMS5003.

Just to confirm it output data each 800ms:

but I see all around people using non blocking read:

  if (pms.read(data))

This give me reads randomly (some reads after reset, no reads at all...)

Any background about what could be the reason? Just trying to figure out how to use the sensor properly