I Manske-extracted harmala alkaloids and obtained 5.5g of freebase, presumably a harmine / harmaline mix.

Then I subjected that to a zinc reduction in HCl (no vinegar at all). The initial pH was 1.8, it quickly went up to 5-ish, so I added more HCl, which brought it down to 1.5, and it rose again to above 5. I added more HCl to pH 1.2.

After 9 hours or so of continuous stirring, the liquid was clear and had no green (or any other color) glow in UV. The pH was again in the 5's.

I always thought both harmine and harmaline glowed green in UV. This experiment has got me baffled. It would indicate one of the following:

1. My rue extract only contains harmaline and no harmine (that would be odd, but when I pH-metrically tried to separate the two, the 'harmine' was always bitter and glowed green in UV).
2. Harmine doesn't glow in UV. Has it been confirmed that it does indeed? Or does it glow much more faintly than harmaline?
3. The reduction reduced not only the harmaline, but also the harmine, to THH or something other non-fluorescent compound. Could it be harmine gets reduced to THH in the presence of stronger acids (HCl), but not acetic acid?

What wavelength is your UV?
The tube type and the LED type give different wavelengths that react differently to harmalas. UV-C wands are different too, IIRC.
Standard color reaction values are given in reference to the standard fluorescent tube type, not the LED type.

It's a cheap Chinese LED flashlight. My THH has never glowed blue in it, but harmaline has a very strong green glow.

Well there ya go, you got a blacklight wavelength that lights up harmaline but not harmine or THH.
And your reduction removed the harmaline glow.
So, success!