Strange effect in TOC/MiniTOC generation

Having answered xxx successfully I became insecure about the process and tested the situation again. I had observed the following since years (windows XP up, FM-8 up to 16), but now I want to find a solution/reason. I have not yet tested in full the new feature "last line indent" - the demos are controversioal for me.

Expecting more than one line for items in generated lists i have > 1 TABs between the <$paratext> and <$pagenum> element on the reference page.

• When the list (e.g TOC) is generated and I look at it, the TABs seem not to be used at all (in this screenshot it is only one TAB):
• Refreshing the screen, re-generating the list - does not change anything.
• No I select the TAB and enter one manually:
• → The TAB  has expanded.
• See the same effect in a list where I have 3 TABs provided to cope with even more lines:
  

→ Why are the generated TABs not expanded in line 2…n ?