Hebrew Nikkud, [mark] feature, FL VI and MS Word vs. Adobe CC

Hi,

I need help figuring out how to use FL VI to make positioning of Hebrew nikkud (diacritics) work in MS Word under Windows.

I created a new font, added matching anchors to two letters and one nikkud sign, let FL VI create the [mark] feature and compiled it. When I exported the font as OTF, nikkud positioning worked in Adobe CC applications but not in MS Word.

So I opened an existing font in which nikkud positioning does work in MS Word and changed the code structure to match the existing font. The result was the same: Adobe CC yes, MS Word no.

So I recompiled the existing font and exported it, to see if nikkud positioning would stop working in MS Word. It didn't stop, it worked just fine.

I should probably add that my new font includes no feature other than [mark], and that the existing font doesn't include other relevant features (it only includes: [aalt], [ccmp], [numr], [dnom] and [frac], on top of [mark]).

Anyone understands this stuff and can help?

Here's the code (the original, FL VI-generated version, is commented out near the end):

feature mark {
# GPOS feature : Mark Positioning
  lookup mark_1 {
    lookupflag RightToLeft;
    markClass uni05B4 <anchor 0 0> @lalala;
    pos base alef
      <anchor 282 0> mark @lalala;
    pos base vav
      <anchor 141 0> mark @lalala;
  } mark_1;
  lookup mark_1;
  script hebr; # Hebrew
  language IWR ; # Hebrew
#  markClass uni05B4 <anchor 0 0> @lalala;
#
#  lookup markLTR {
#      pos base alef
#          <anchor 282 0> mark @lalala;
#      pos base vav
#          <anchor 141 0> mark @lalala;
#  } markLTR;
#
#  lookup markLTR;
} mark;