Ok. Got it.

I removed everything from the que. Saved the game, reloaded.

I put in only 3 units (max unit pool). 1 Turkish Archer, 1 Turcoman Horse, 1 Sipahi. The result was: all three came out with manpower retrained, and only the Turkish Archer & the Turcoman Horse cmae out with armor upgrade in addition. That is perfect.

So what was the problem ?

That's the issue I have not been able to identify. I tried the following:

1. Put in ALL the turcomen to retrain, all 8 of them plus all the Sipahi. More units than are available in the unit pool.

Result: It still worked.

2. I put in only those units that are available in the unit pool.

Result: It still worked.

WORKAROUND: reload the game.

I'm almost certain however that the bug does indeed occur when you put in a que of units to retrain, more than are available. It could also be that the bug occurs when there is a combination of factors, armor, manpower retrain plus lack of manpower. Can't be verified until it occurs again. The workaround is easy enough.

Thanks Rothe you pointed me in the right direction.