You have got me here! I’ll give you my thought processes
Flycatcher - Muscicapidae; a lot of species but nothing that stands out. Mind you, is it a Muscicapid that doesn’t have Flycatcher in the name? Some good species there…
There again, there are other Flycatchers, such as Paradise Flycatcher which are not Muscicapids and might be more likely…
I have not birdied Mainland South East Asia, and not researched Myanmar, so the altitude info isn’t helping.
Unless it doesn’t have Flycatcher in the name, I think I need a lot of help; maybe someone else has an idea or two.