If I understand your post correctly, that when you put on your left turn signal, the rear bulb flashes but the front doesn't, then I suspect a wire fault or corrected connector between where the wire splits from front to rear blinker supply wires.
However then you wrote the dash indicator doesn't flash, which would instead be consistent with a problem with the multi-function switch or a wire fault BEFORE the point where it could get to the rear blinker, so the rear blinker shouldn't work.
Is it possible that the left rear turn signal now does not work, maybe it did when this started but now it's worse?
Since I just had to clean out my multi-function switch for a failing right blinker, I'm inclined to suspect yours has gone bad. Instead of getting a new one I just took the T10 screws out, cleaned the contacts with a petroleum based metal polish (brasso, or you could use gasoline to clean the hardened grease off then your choice of abrasive to clean the oxidized copper off), then put a light coat of silicone dielectric grease on the contacts.
There's a video on youtube that could help, but all it basically shows is to lay it flat on the table to take the screws out, take the cover off with care so nothing inside comes flying out.
Anyway, cleaning the switch out is *free* but for a few minutes of your time. If that doesn't help, then I'd look at other suspects.
See the link in my sig for more diagrams but that one is attached.