FCP saved project to Desktop then transferred to USB as 1., MP4 and 2., MOV. neither is recognized on LG smart TV

This situation is commonly seen, and it has nothing to do with FCP. In general, "smart" TVs have fairly weak CPUs relative to a laptop, and have highly-specific requirements about what video file characteristics they will accept.

More is involved than volume format of the thumb drive, and more is involved than a simple high-level spec like H.264 or HEVC. Typical "smart" TVs often require a very specific range of characteristics such as GOP length, bitrate, bit depth, container type, etc. Without knowing these specific requirements, it's easily possible to produce a video file that still doesn't play properly on the TV.

Check the manual and any manufacturer info about specifications required for playback of 4k video files.

If the manual lacks sufficient information, you will have to contact the manufacturer about their detailed video file criteria for smooth 4 K video file playback. We need highly specific information here.

A laptop or desktop or even an iPhone have vastly more powerful CPUs than a smart TV and can handle a wide range of encoding formats. It's possible your TV is optimized for a narrow range of codecs or requires specific encoding criteria.

Tell your TV manufacturer or support channel for that TV that you need detailed technical specs for the playback requirements of video files on USB. That includes codec, resolution, color space, bit rate, frame rate, bit depth, chroma subsampling, container type (e.g, MP4, Quicktime, etc). Given that info, it is likely possible to produce a compatible video file using either FCP, Compressor, or other third-party utilities such as ShutterEncoder or Handbrake.

Check the TV manual which format it supports:

USB drive: FAT, exFAT, NTFS, etc?

Movie wrapper: .mp4, .m4v, .mov, .mkv, etc?

Movie codec: H.264/AVC, H.265/HEVC, MPEG-2, AV1, VP9, etc?

Audio codec: AAC, PCM, MP3, etc?

Disk Utility can format to several schemes: APFS, MacOS Extended, FAT and ExFAT. You want to format the thumb drive to what the TV will accept, most likely FAT or ExFAT.

d907ie wrote:

Many thanks! It appears that my iMAC formats to exFAT only. Is that right? I also didn't see an option to format the thumb drive, only erase or restore. So, I'm assuming the thumb drive is formatted to exFAT and I'll try again...

peace

There are other formats:

The above Thumb drive is currently formatted to MS-DOS (FAT32).

ExFAT means Extended FAT format; allowing larger file sizes to be added.

You do need to erase a drive to change the format.

Make sure you have a backup of any important files before proceeding:

As Terryb says, Check the formats the TV supports so it will work seamlessly.

YMMV in this area.

Al

d907ie wrote:

exFAT sounds familiar, but I will check again. Let's say it is exFAT, I will be back to you about how FCP makes that change, or would I need another bit of software to convert.

FCPro does not do any formatting.

You do not need additional third party software.

Your Mac has a pre-installed app called Disc Utility, this is what is used to format a disc or thumb drive to the desired format.

Macintosh HD>Applications>Utilities>Disc Utility

Al

Instead of delving into a lot of technical details, why not tell us specifically the model of your TV?

Perhaps with that information we can help you get the information you need without suffering through too many technical details.