Issues about SamplerProcessor, rendered audio, and VST3 plugins loading .fxp presets

[heqi201255]

Hi, I'm working on my project that uses DawDreamer as the render engine. Here are some issues I met:

1. SamplerProcessor does not work properly: initially I found the rendered audio from SamplerProcessor are all click sounds like this:

The midi is an arp loop and the audio data is a short guitar sample in "wav" format, so I think the midi is loaded properly, then I thought it might be the initial parameter states got wrong, so I checked them and I tried to set the parameters, but it didn't work: I tried "1", "1.0", "True" for the "Amp Active" parameter to get it turned on, but all of them didn't work.

2. PlaybackWarpProcessor will cut the transient of the audio: I gave a kick sample to the playbackwarp processor and I set the clip positions so that it renders a kick loop, but I found the transient of the kick got reduced a lot, don't know if it's a rubberband issue but I did not change the transpose and tempo_ratio settings:
   Original Kick:

Rendered Kick:

3. Loading Serum plugin in VST3 format could not load .fxp preset files: I think Serum's presets are all in "fxp" format, and I can load them into VST3 Serum in other DAWs. Calling "load_preset()" won't throw any errors but the preset is just not loaded into the plugin, I haven't tested this on other plugins with dawdreamer.