Please help us by saying exactly which plugins have a problem, and telling us exactly what the error message says. Are you seeing a message like this in High Pass Filter and Low Pass Filter
Those are the only Nyquist plugins that I find a problem with. It happens if Audacity runs in any language other than English, either if I change language in Audacity Preferences, or leave the language in Audacity Preferences set to “System” but change the Windows Region and Format language.
The message appears translated into the language that is set, so that translation must be coming from wxWidgets translations.
If you just OK the message, High Pass or Low Pass will open and as far as I can tell the effect will apply normally.
If I change language back to English the message persists, this time displaying in English. Restarting Audacity does not stop the message appearing. To stop the message appearing you can quit Audacity then delete audacity.cfg or pluginsettings.cfg. Alternatively if Windows Region and Language is set to English, set the language in Audacity Preferences to “System” and the message will disappear.
Sometimes, but not always, Generate > Tone produces similar messages when Audacity is not running in English.
I also notice that when the Audacity language is changed to other than English, the name of the “Delay” effect in the Effect menu becomes translated - again it must be pulling that translation from wxWidgets.
The problem is not with the plugins. The problem is with the underlying code that handles all effects, which is currently undergoing a major rewrite. This is very complex code and I would guess that the rewrite is likely to take several weeks to complete. Once complete it will require rigorous testing, but at this stage it is no surprise that there are lots of bugs and breakages in it. If you took your car to a mechanic to have a complete overhaul of the engine, you would not expect to be able to drive it until the overhaul is complete, and then you expect that it would need a bit of running in and tuning to complete the job.
Nightly builds are NOT intended for production work. Do not use nightly builds for production work. Nightly builds are “alpha” status and are NOT intended for general use. Alpha builds are for developers and alpha testers. They are NOT intended for and should NOT be used if you require a tested and reliable application. Much of the time the nightly builds will include “work in progress” which may be incomplete and will certainly be untested so they are by their nature NOT suitable for general use.
Please see these references for more information: http://en.wikipedia.org/wiki/Software_release_life_cycle http://en.wikipedia.org/wiki/Software_testing#Alpha.2C_Beta.2C_and_Gamma_testing
Older versions of the alpha builds are stored so you could continue using the new features that do work by going back to the alpha build before the problem started.
If you click the link on the download page that says “View Audacity latest commit changes” you can see the changes that were made at the point each alpha was built, and you can see if any of the latest commits say that they have fixed problems with the effects.
If you don’t understand what any of that means then you probably should not be using alpha builds.