Thank you for your attention to my question.
The problem appeared to be more special and slightly less critical then I thought it to be firstly.
There are two issues in fact (not related maybe):
- The first one is present with some vst3 plugins only. As an example let's take Fircomp_2 by Jon V Audio (you can get it here https://drive.google.com/file/d/1n-8K5M ... sp=sharing, it's potable and licensed to me, the only thing you need to make it work is to copy vst3 file to your drive).
This plugin has 0 spl latency with 'lookahead' mode OFF, and 64 spl latency with 'lookahead' mode ON.
When you change the mode in Fircomp_2, the change of plugin's latency isn't seen by Mulab until you switch Mulab's 'process' button OFF and then back ON.
With Reaper this plug works nice and PDC changes immediately after you change the 'lookahead' mode state.
Some other freeware examples showing the same thing:
PTEq-X by Ignite Amps
Molotok, Nova, Slick EQ by Tokyo Dawn Records*
- The second one. Mulab ignores manual plugin latency setting for VST3-s (I've tested this issue with ~10 different VST3-s from different manufacturers with the same result).
Here is Mulab project with Fircomp_2 plugin inserted and 1234 spl latency manually set for it. https://drive.google.com/file/d/1n7S8XL ... drive_link
This setting has no affect.
I'm on Windows10, my DAW is Reaper v7.02. If you need some more information on my system and DAW please let me know.
Thank you.
*UPD: with VST3-s from TDR latency parameter doesn't change to correct value even after "reloading" Mulab's 'process' button.

