I've tried to finally migrate over to default recording as opposed to prec and I can't, for the life of me, get the mark function to work. I've tried changing read only things, tried changing the way the bind is written, tried different keys to bind it to and nothing happens. Even when I know it's recording and I manually type it into console, nothing happens. The demos record no problem, but bookmark never works. Here's my autoexec if it will help at all: https://i.gyazo.com/54ee0e726d3553aa2b8184d69568c7bd.png
Try placing something after the "ds_mark" i.e something like bind ] "ds_mark frag" also make sure that you're checking the C:\Program Files (x86)\Steam\steamapps\common\Team Fortress 2\tf\demos\_events.txt document and if it doesnt show try deleting it.