You may be running into one of several problems...
If the quest is one in which there are different options (do x OR do y), then you have to satisfy fully one of the options or the other (not a mix of both). If you have partially completed one, you can fully complete the other, but it will not show any progress until you do more of the second thing, or fully complete it.
For example: Gain 4 Combining Catalysts OR Spend 20 Knowlege Points. If you spend 10 KP and then collect 1 CC, it will still just show how many KPs you have spent. If you collect all 4 CCs, the quest will complete even though it never showed how many CC of the 4 you had collected, since you still had more KP donated.
Also, gaining enchantments only works when you collect them (sorry if this is too basic, just trying to hit all the points).
If none of these seem to explain your issue, a support ticket is warranted. Or, give us some further details such as the specific quest wording you are trying to fulfill and/or some screenshots.