I had eggpoints from Newegg from when I originally purchase my mavic.  Went to see what filters they had and took a chance on the freewell multicoated set with 6 filters, including a couple of PL/ND combos.  The filters were $60 less than the top brands and they said in their ad the filters passed the gimble test, so I took a shot.  I did have to wait 8 days for shipping from overseas, but I wasn't in a big hurry, so not a big deal.  Also, because I already had $64 worth of egg-points, this filter set ended up costing me $53, so that's a win too.
They arrived today and I sadly only had time to throw one on and check it before I headed out for a trip.  It was a sunny day and I used the ND16/CP.  It slid on easily enough and had a snug set into the home position so it became clear the filter was seated well.  I fired up the mavic and it went through the gimbal test without issue.  I only had a couple minutes for a test flight and found it was nice to finally get to drop the shutter speed down to a more cinematic level, all the while having more saturation in the sky and the broadleaf tress that are close by.  I have seen in the past how much a PL can deepen the sky but the trees were surprising.  I hadn't realized how much more green the leaves are without the reflection off of them.  After flight, removing the filter was easy enough...just a gentle tug and it came loose...but still, it felt strong enough of a fit that I doubt it'll come loose on its own.
FYI, I installed and removed the filter while I had the gimble lock in place as it'll hold the camera more secure than I will...I think.
The kit did come with the 6 filters, all multicoat, a carrying case that actually seems a bit overkill and takes up more room than it could, and also a cleaning pen.  
For now, I am NOT endorsing the product...I only tested one filter and in the few minutes I had, it really was not thorough at all.  However, if others are considering the less expensive multi coated set from free well, I am sure you'll be happy to see that my experience has started out positive.  I will come back to the forum with more updates when I return from my trip and have time to test.
And as there are a bunch of different filters out there, these are the ones I purchased:  
Freewell Lens Filter 6Pack for DJI MAVIC PRO-Newegg.com