Web audio API: portion of app works as intended only after getUserMedia()

Flow:

1 user uploads audio

2 user selects an audio filter (in this case, a BiquadFilters) for the audio

3 user plays the audio

In a previous version of my app, I used to ask the user for permission to access the microphone. With this code included (navigator.mediaDevices.gerUserMedia) the portion of my app which loads lowpass and highpass biquad filter nodes worked perfectly.

Why don't I just use getUserMedia, then? Because it causes more problems than it solves: recording problems, Firefox incompatibility (it only works in Chrome), etc.

The fact that it works after running getUserMedia let's me know that there's nothing wrong with my code which deals with the audio graph.

I'm hoping to find someone who can help with this problem.

Thanks in advance