Get rid of the orig left rear speaker.....if prob then persists, the speaker(s) that failed affect or have damaged your L output......don’t screw around with this LR speaker, as your output works now/fails shortly afterward might well become permanent if you continue to use the speaker that was in place when this started.
The original left-rear speaker is now the left-front speaker. It appeared to be fine.
I hooked it up to a home receiver and it functioned normally, whereas the original left-front had no woofer (only tweeter) sound. I got rid of the original left-front speaker.
In my truck, the sound from the left front speaker isn’t as noticeable, so the original (L-F) speaker could have been that way for awhile.