Ambience settings messing up

[MaXyM]

hello
While trying Reaper since a year ago or so, I still feel to be beginner, so sorry if I'm reporting something obvious.

In my recent project I decided to use Ambience reverb plugin. In fact, 3 instances based on the same preset, but each modified a bit. After a while I figured out, that some settings of those plugins are messed out.
Of course, the first thought was it's my fault. But after problem returns back again, I figured out that something is wrong with the either with plugin or the DAW.

At first I noticed, that sometimes, switching between presets, some parameters doesn't change while other does.
At secondly I found, that if I load a preset, modify one parameter (let's say the length of reverb) then switch to another preset and forth, all possible parameters are being changed, but the manually changed value returns to what I've set. In my understanding, it should load all values from selected preset regardless I changes any in the past.

I did a test case:
1. created empty project
2. created 3 tracks, with one instance of Ambience reverb on each
3. I loaded the same preset to each instance.
4. and changed reverb length to 1, 2 and 3 seconds respectively
5. saved project, closed reper, then re-open the project again - everything ok so far

6. I started to play with changed parameter in one of the reverbs, also loading forth and back presets from the list. At the end I returned to original preset (which seems to remember my initial reverb length)
7. Saved project, closed Reaper.
8. After re-opening the project, I opened all 3 instances of reverbs seeing that despite the all of them have marked a preset I've initially/recently selected as active, several reverbation values (incl manually set) doesn't match selected preset nor my manually set value.

This is the only plugin I found behaves this way.

Question is, is it plugin bug (how plugins might affect each other?). Is it Reaper glitch? Maybe it's being exposed only in specific situations/configurations etc.

with regards