Hello
Even if it seems to me that it is a nonsense to use them together, a French user fell on a bug that appears if we use tabs + tab leadins + tangent leadin.
In this case an extra leadin (an half circle) is added on the toolpath leadin at the last or two last paths. It is superimposed on the normal leadin for this level as we can see on the picture 2 ... first an half circle is cut, then the normal leadin is cut.
++
David
edit: same bug on 0.98 .. and in fact the extra circle leadin appears on all level that are bellow the tabs level.