It’s not a bug, vandamme. As I explained, the ‘Starts voice’ property can only be set if it is not in conflict with something happening earlier. In your example, the eighth rest at the beginning of the second beat is forced to appear (it has the ‘Force position and duration’ property set). Therefore the eighth note that follows the rest is not the first note in the voice: the rest that precedes it is. You can no more set ‘Starts voice’ on this note than you can e.g. the third note in a bar of 4/4 with four quarter notes in it. If you need to start the voice on the eighth note (which, as discussed, is a very bad idea since the player will have no idea what the rhythm should be), then select the eighth rest that has ‘Force position and duration’ set, and delete it by hitting Delete: the rest will not itself disappear, but the explicit rest will be replaced by an implicit rest. Now you can select the following eighth note and set the ‘Starts voice’ property.