For a project on Project hub, i had try to use the Liquidcrystal libraries with the Arduino cloud, the results was that the LCD stop to works when the sketch reach the loop API , moreover if setup if call first the begin of the LCD and after the begin of arduino cloud the LCD is not correctly initialized.
could you provide your code? There's no reason for the library not to work during the loop if you are handing the code correctly.
What sounds odd, though, is the issue you have with the LCD not initialising correctly after you start the Arduino IoT Cloud.
I supposed the display you have works normally when not used with IoT Cloud. Let's solve this together :)