Hello,
I’ve the same problem on my Fairphone, the problem is on some custom rom ( Like lineage, /e/, CalyxOS ). I restore fairphone OS and all is working.
I do a magisk mod and now it’s working but it’s not really fixed, i’ve just do a dirty mod on the mixer_path file. I don’t know where the problem is. The problem is not the file because it’s the same file on fairphone os