You don’t load a loop into a Pattern. We are assuming here that when you say “loop” here you are referring to an Audio clip set loop playback. (Because all Scenes in the Pattern Sequencer “loop” by default).

The only data in the sequencer is always MIDI data. Never audio data. Never ever anything but MIDI events.
As you know, MIDI data can be used to trigger the playback of audio (that is what a sequencer does). I know you know all of this, so when you ask the question, just put together what you already know...

Put your audio loop into a New Waveform, place that Waveform in a Part, place that Part in your Performance.
A single Part has 128 Keys, C-2 through G8. When you want the audio to sound, press a Key at the velocity that causes it to playback at the volume you desire — of course, you could place that note in a Pattern Sequence.

Create your audio loop and set your loop points prior to loading it into a MONTAGE Waveform.
If you load a looping Audio clip into the MONTAGE it will playback as a looping audio clip - you must set the Element parameters like the AEG to support your playback requirements.

It is highly recommended you import the audio loop to a Drum Kit KEY, because it can be set to ignore Note-Off (making it unnecessary to hold you finger on the KEY to make it continue sounding) and Drum Keys can be set so DECAY 2 TIME can be set to “HOLD” (making it possible for the audio loop to play endlessly), it also allows for the Key to be placed in what is called an Alternate Group (like the three Hihats :closed, pedal and open which are in the same Alternate Group — only one sound in a Group can sound at a time — this way one audio loop can be made to replace another, and you can setup a “silent Key” that acts as a ‘stop play’ Key.

If you get stuck, post back here.

thank you