What order do you do your exercises in?
If front lever is near the end and you're getting very good quality out of your first exercises your front lever ma suffer.
That is what I've seen the most... if people do say back lever, planche, front lever in that order it's expected that front lever will suffer some being in the back of your exercise order.
You generally want the exercise you want to improve the MOST to be first in the list.
That said, even if it is first sometimes exercises stall out like that for a couple weeks but then they usually jump up in progression. Since it's been 6 weeks apparently this has not been the case. You may want to consider adding some specific work on the back muscles such as the external rotators, retracts, posterior delts.
Also, you do not need to focus on retracting the scaps. Just go into inverted hang and then pull your hands forwards towards your hips while your body starts descending. There's no specific technique as long as you don't bend your arms -- whatever feels more comfortable.