Can't export videos in original format as getting error 'assertion failed' Lr Classic 9.1
I'm trying to export videos in original format (if you ask why, I make the selection of the videos in lightroom, colour-tag them and then export them), but I always get the error "assertion failed". If I rename them it still doesn't work, it only works if I change the format, which I don't like (the original are some .mov and some .mts files, if I try only with .mov I get the same error).
This is my software/hardware:
I'm working with Lightroom CC 9.1 and MacOS 10
Lightroom Classic version: 9.1 [ 201911291132-64cf80b4 ]
License: Creative Cloud
Language setting: en-GB
Operating system: Mac OS 10
Version: 10.15.2 [19C57]
Application architecture: x64
Logical processor count: 4
Processor speed: 3,8 GHz
Built-in memory: 8.192,0 MB
Real memory available to Lightroom: 8.192,0 MB
Real memory used by Lightroom: 1.206,1 MB (14,7%)
Virtual memory used by Lightroom: 12.773,6 MB
Memory cache size: 361,9MB
Internal Camera Raw version: 12.1 [ 351 ]
Maximum thread count used by Camera Raw: 3
Camera Raw SIMD optimization: SSE2,AVX,AVX2
Camera Raw virtual memory: 1270MB / 4095MB (31%)
Camera Raw real memory: 1306MB / 8192MB (15%)
Displays: 1) 5120x2880, 2) 1920x1080
Graphics Processor Info:
Metal: AMD Radeon Pro 580
Any ideas? Thanks in advance.

Try, Do nothing.