Hello !
I'm using mechjeb for years and never had any problems but since few weeks, it became just unusable.
The problem is about the burn timing, it always starst the burns at T0 (just at the node and not before), and reinstalling ksp and mechjeb isn't doing anything (knowing that i'm not using a lot of mods : only one or two for aesthetic, flight engineer, mechjeb and that's all) and this problems is happening with every engines and crafts i tried (i have only stock parts). I've seen a precedent subject almost like mine but without any real answers and the problems seemed to be coming from some modded parts or in my case ANY parts of any vessel is involved, mechjeb just can't do a burn. (Landing and stuffs are ok it's just the burns). It's not a huge problem indeed but the precision of mechjeb burns are very usefull sometimes ^^.
Thanks in advance for your help