MIDI routing in sandboxed plugins - delays and out of sync

I remember when I was trying to use FL plugin inside Renoise (that vst that allows to use FL instruments inside other DAWs). I was surprised how bad it works in Renoise - everything was uneven, some notes plays with a delay etc. But I was thinking that it’s because stupid FL wrapper/plugin.

Today I tested something different. As you may know, some synths have midi output and you can control other plugins using that. So I tested new feature in some synth (commercial) - routing MIDI to other synth. One synth only produces MIDI ARP output and second synth plays that MIDI notes. And they’re out of sync. Not very much, but still. A little less when number of ticks per line was increased, but even then equal spaces between ARP notes sound like with random small delays.

So I tested few oher synths that has midi output and one arp plugin. Also I changed destination plugins as well. No matter how I was triying to pair them or setup (static buffers or not) - notes plays uneven, out of sync. Not a big difference, but noticeable.

Can it be fixed?

IMPORTANT - problem is when plugins are in Sandboxed mode.