it appears filament-like to not go past the Bowden splitter at times. sometimes it works other times it doesn't. what has consistently not worked is swapping filaments. it gets stuck in the extruder, which I have as a direct drive. Mind you the direct path is not entirely straight but it does load fine. Silks seem to be worse with this and the stock unload g code with silks causes a longer strand than with pla+. I usually print at 210 per the ender 3 pro profile in prusa slicer 2.6 alpha.
I have tried direct mode and it was another headache in itself. This might be a bug in the MK3 firmware. After loading one tool by pressing the button myself I noticed it won't respond right away after swapping and it actually swaps to another tool I didn't intend. Making direct mode basically unusable.
I might try a different bowden splitter but there's likely a bug that needs to be worked out for direct mode.
What do the tips of the filament look like? Tip shaping is the most important thing that needs to be take care of so that the filament doesn't swell and jam in the rest of the system.
See our FAQ #10 for hints. Also, take a look the 3DClippy and see if that can help if tip shaping is an issue... with it, you can simply cut the tips off without worrying about trying to shape them. Lastly... about the possible bug... can you show me what you mean in a video, or give me steps to reproduce it. Also, are you sure you're not in some other mode of operation... there are 3 modes. Mode 1 is extruder replacement mode... Mode 2 is extruder load/unload and Mode 3 is identical to Mode 2, except that it requires you press the buttons for as long as the filament needs to move... so it overrides the default 10/11 inch unload/load and instead allows you to set it to any distance. Also, make sure the commands you're sending are timed correctly so that you hear the vibrations indicating which command is active. Take a look at the bottom of the Mk3 GCode Generator Page for details.