@kako05 I've updated the plugin to version 6.0.0, basically, I've taken a few things into consideration to improve the performance when transitioning between scenes( especially menu's ), so hopefully this should fix whatever issue was there before, I didn't have time to test compatability with Galv's preloader, so I can't say for sure if it's a compatability. 
Also @AdamSakuru The problem you were encountering was due to the cacheLimit from mv 1.6.0, by default, there should be a plugin that comes with every new game you create called something like "Community Basic", this plugin comes with a feature to let you set the maximum cache size.
However I realized not everyone uses this plugin, so I've built my own cacheLimit modifier built into the plugin
I've also added another plugin parameter to outright disable the cache limit value( which I wouldn't recommend too much, however the option now exists! ). Either of these new features should work to resolve the issue you were having, however 6.0.0, was well... honestly a bit rushed ^^; and the thing is I went through the entire plugin and nearly rewrote large chunks of it to improve performance, loading times, as well as readability of the code, so 6.0.0 may be a little unstable, however during what time I had to test it it seemed pretty solid, however If any bugs should arise, I may not be able to resolve them as quickly as I'd like, so for that reason I've left 5.5.1( I know it still says 5.5.0 in the plugin itself sorry T__T ), available for download as well!
Also @AdamSakuru The problem you were encountering was due to the cacheLimit from mv 1.6.0, by default, there should be a plugin that comes with every new game you create called something like "Community Basic", this plugin comes with a feature to let you set the maximum cache size.
However I realized not everyone uses this plugin, so I've built my own cacheLimit modifier built into the plugin