Hi anto, this is a bug in MoI in the current beta - when doing curve-to-curve flow there can be an unwanted rotation that happens.

You can avoid it from happening currently by rotating both the object to be flowed and also both curves so the entire thing is flat in the world x/y plane rather than being arranged vertically. Then when you do the flow it should behave ok and then rotate the result back by 90 degrees from a side view.

In the next beta this will be fixed up so that your original case should work properly and not need to have both curves in the world x/y plane anymore.

If you'd like to post your 3DM model file I will test it to make sure the fix is working properly for your case.

Thanks, - Michael