I purchased the Lexar Professional 1800x because of the speed for 4K video. It is a microSDXC UHS-II card with a speed of 270MB/s. When I put the card in the bird, I get an error. I have performed a full format of the card. I also spoke with the Lexar customer service rep and reports no problem with the card and the Pro. It works fine in my computer. Is there a compatibility issue with the card and the Pro? My other cards work great.

I am having the same problem.
Lexar Professional 1800x microSDXC UHS-II, Phantom 4 Pro+

Similar problem here with the:
Lexar Professional 1000x microSDXC UHS-3
and the Phantom 4 Pro+

An UHS-1 class microSD seems to work better in general with the Phantom 4 Pro...

I have have the same issue with the Lexar Professional 1800x microSDHC 32GB UHS-II.
Does not recognize the cards when put on the bird. I guess i have to use them for other photography purposes.

I messed around with the Lexar Pro 128GB UHS-II, U-3, Class 10, i formatted it in my7 mac, i tried formatting it on the drone and nothing, every now and then it would read the card for about 5 secs before telling me the initialization failed.  I had also purchased a SanDisk 64GB Extreme Pro card and it works perfectly.  I have heard lots of issues with the Lexar cards and i would recommend, just stay away from them.

On the recommendation of others i have ordered a Samsung Pro 128GB, card, apparently they work well in the P4P so as soon as it arrives i can let you know.  For the moment the Sandisk 64GB Extreme Pro  works perfectly and it provides 1hour and 45 minutes at 2.7 60fps so that is plenty for a reasonable flight.

I am sending mine back to B&H and getting a SanDisk instead. I know that card will work.

same problem i did bought two Lexar Pro microSDHC 32GB 1800x and they just hand the camera after i start recording... and then i have to restart again .... even the lexar 16 gb 633x UHS 1 card is working great ... what a shame that a 1800x card showing error and finally dead!!! still talking to lexar i wish they replace the card...

As far as I am aware, the UHS-II cards are not compatible with the Phantom aircraft. They use an extra row of contacts that the aircraft is not equipped to handle. If you look at the DJI specs, they only mention UHS-I ratings.

Same for me, the cards worked fine in the P4.

Same problem here.
Works on my P4A, but doesnt work on P4P.