I'm begging you. It's nice that we don't always lose our materials, but this has to be the most frustrating part of the game I've encountered. (especially after my internet turning into swiss cheese)
If you D/C during a boss, you, and possibly your entire team, dies. Just some gear damage. If you D/C during a levequest, you might die, but the leve will still be there. At worst, you lose the allowance and can immediately retry. But when crafting... you could potentially lose a lot of gil. I haven't been this frustrated with FFXIV since 1.0, when D/Cing would fail your leve.
Maybe it's a memory issue. Maybe they don't want thousands of people suspending synths and running around. In that case, give me an ultimatum upon being interrupted or logging back in.
"You were in the middle of Synthesizing [item]. Please Abandon or Continue the synthesis."
Abandoning would give you the same results we have now. Continuing would give you the same Durability, Progress, CP, and buffs that you had beforehand. Can anybody see any issues with that?