Little Upsilon: Mar 11 2832
Factory Maintenance Units 3.24M SC$ per unit
So, assuming 100 quality, for 900K units,
that's about 2.88T - 3T SC$
Did the finance page show a transaction at all, and were you buying other things? If there were some cash moving, like say for some 'pending deliveries' of other items from a while ago, it's possible those delivered, and the cash kind of 'canceled out'. It's not an enormous amount, like say 20-30T SC$ which a spending space wouldn't even come close to, but in the 2-3T SC$ range, if you bought, say, some other items at high quality then the cost could be similar, especially with a spending space booster.
The other thing is the 'enterprise auto-cash transfer', which when an enterprise has extra cash, it will send that cash --into-- the corporations...(yeah, find that one in the 'documentation', haha)...so, maybe it went there, too.
Or, maybe you didn't pay your 'Enterprise Tax' during your 'vacation', and now 'Gamemaster' is collecting back..haha ;).