3.0.2 bugging LRc

Everything went fine (even if I still don’t see how to “Sync”) but now doing Control N suddenly gets me a LR box: Loading Negative lab pro with “operation ended” that remains visible but unoperative : The classic Conver negative board doesn’t convert, the operation is blocked and I have to force quit LR.
Does it on all images now.

I’ve now taken the 2.4 and 3.0.2 NLP plugins from LrC off since it makes Lr freeze (sent you a screenshot by mail) and tried to download a new NLP plugin from your site but I can’t seem to get the link to my mail (and I need to convert some B&W real soon)