The reason why others have not that problem like you is probably very simple, its one of two reasons. Its either a bug in A6/A7 that got fixed in the versions above 7.07, or its a bug in your code that behaves differently in different versions. A7 is 100% code compatible means bug free code, but with some little bug, like using an undefined return value, it can behave different.
In the bug list of a7.07 Beta for example you can see this:
"The ent_setmesh function caused a wrong collision behavior when the new mesh had a different size (triangle or vertex number) than the old mesh and the scale of the entity was changed afterwards (all A7 versions; fixed in A7.08.2). Workaround: Change the entity scale one frame before setting a new mesh."
So if you used ent_mesh you get a different behavior after 7.07.
I think it is nonsense to stick to an old version which was even a beta version just to "preserve" the behavior of a certain bug, better find what this bug is, fix it and move on to the newer and better versions!