Finalize button not working on IDA 7.5

[shrddr]

The vftable structure does get created, but the class itself doesn't. Output Window:

Traceback (most recent call last):
  File "...plugins\HexRaysPyTools\forms.py", line 93, in <lambda>
    btn_finalize.clicked.connect(lambda: self.structure_model.finalize())
  File "...plugins\HexRaysPyTools\core\temporary_structure.py", line 692, in finalize
    if self.pack():
  File "...plugins\HexRaysPyTools\core\temporary_structure.py", line 557, in pack
    cdecl = idaapi.ask_text(0x10000, '#pragma pack(push, 1)\n' + cdecl, "The following new type will be created")
TypeError: can only concatenate str (not "NoneType") to str

Here is the line. Any tips how to make idaapi.print_tinfo() return something other than None? This function is listed in IDAPython docs, but with no description, maybe obsolete?