Works just fine here. Are you using the latest version of the plugin?

HY-Reso can no longer be downloaded, but TAL-Filter-2 works both in 32-bit and 64-bit flavour here. If a plugin fails to report its parameter state, it is rarely a problem that's exclusive to OpenMPT, so please try if e.g. http://www.hermannseib.com/english/vsthost.htm has the same problem.

Alright, I think you're on the right track. vsthost doesn't save the plugin settings either. I just tried on Windows 7, and it does the same thing. I'm curious how you got it to work.

Just to get an idea what the plugin might be doing differently on your systems, can you save the plugin bank in either VSTHost or OpenMPT's plugin editor and attach it to this bug report (zip or 7z the file first)?

An interesting thing I found, I can load the plugin bank and it works correctly! But it would be a pain loading the bank every single time I open my project.

Okay, the fxb file looks as expected, so it would be weird if it could not be loaded after all. Can you create an empty module, put the plugin in there, save it and then upload that module (given that the parameters don't load properly)?

I see that the knobs on the plugin do save, but not the points or lines.

So what is it supposed to look like? When loading that file, I see the envelope of the default preset. Did you customize the envelope?

EDIT: Having a closer look at the module file, it seems like the plugin preset data was not embedded. While that still sounds like a plugin issue more than an OpenMPT issue, maybe we can somehow find out why it doesn't work for you. I'll try to think of some way of doing that.

Yes, I did customize the envelope to a bunch of random points before uploading the file. Thanks for responding to this issue! I hope you can come up with something.

Please try this modified build to hopefully get some clues: https://sagagames.de/stuff/mptrack.exe
When saving a module, it should show you a message box containing a few diagnostic messages. Press Ctrl+C while the message box is showing and then paste the contents here.
Since the message will be shown for any VST plugin, it's best to once again try it with a fresh module only containing this plugin.

Open ModPlug Tracker - Error

ProgramsAreChunks() = 1
SaveAllParameters()

OK

Okay, now that's an unexpected result... Please download the executable again and do the same thing with the new executable.

ProgramsAreChunks() = 1
effIdentify = 0
effIdentify expected = 4e764566
SaveAllParameters()

Okay, I just found out that that I did in fact not download the latest version of TAL-Filter (somehow the colourful platform icons next to the old version downloads caught my eyes more easily than the grey download buttons for the current version...).
I can now confirm that the current version of TAL-Filter returns 0 for effIdentify. This function is deprecated and I guess now the first plugins start not returning the proper value for it anymore. In the next build, I'm going to ignore effIdentify entirely, which should make saving the parameters for this plugin possible again.

Fixed in r8120 / OpenMPT 1.27.00.45.

You can now find an up-to-date test build that works with TAL-Filter-2 and doesn't show the test message box at https://builds.openmpt.org/builds/auto/openmpt-win64/