3 instances of plugin in old project have lost some settings

(NB. Title and content slightly changed from original post, following investigation)
 
I have an old project, probably from 8.5, where I had 1 plugin - Image Line's Poizone v2 - which was set to 3 different sounds. At that time it all sounded fine, loaded and saved okay, and I exported the audio at that time without problems.
 
Fast forward to today. I open the project in Platinum, and although the first instance of Poizone sounds precisely as it should, the 2nd and 3rd instances have very similar settings as the 1st instance. At first I thought it was just reusing exactly the same settings for all 3 plugins, but on closer inspection, it looks like it's lost part of the data. The envelope and amplifier settings differ from instance to instance but all the other submodules appear to just be just at the default (perhaps for the patch, perhaps for the synth, not sure).
 
This means the track sounds completely wrong, and is broken until I can find a way to restore the previous settings.
 
Has anybody else encountered this? Is there any sort of workaround, short of me reinstalling 8.5 and hoping it opens properly there?

Not sure how incremental saving would work, since I'm pretty sure the file itself is okay, as it worked fine back when it was created. It seems like Platinum is just not applying some of the preset data. An alternative hypothesis is that Poizone is choosing not to accept all of the saved preset data, perhaps because I have a slightly different version to before.

Kylotan
Not sure how incremental saving would work, since I'm pretty sure the file itself is okay, as it worked fine back when it was created. It seems like Platinum is just not applying some of the preset data. An alternative hypothesis is that Poizone is choosing not to accept all of the saved preset data, perhaps because I have a slightly different version to before.

Ah ok, maybe, I don't know.
But there is difference if it worked when it was created, or if it worked when it was created, saved and reopened. If last, than it is not the case that I've thought about, because I have other cases.

You can install the old 8.5 and open the Cakewalk projectfiles in 8.5.
Then you can save the presets within the plugin to a file as preset.
I always advise to save the presets within the plugins to files before installing a new version of software.

Kylotan
I have far too many projects to save every instance of every plugin as a preset. Life's too short.

I only do it for synths. Not regular plugins.
 
Dan