'unexpected inability' is correct and can be used in written English.
You would use it to refer to an inability to do something (e.g. an ability to complete a task or achieve an objective) that arises unexpectedly. For example, "Due to an unexpected inability to keep up with demand, the company was forced to downsize."
For banks, the unexpected inability to trade particular stocks disrupted complicated trading strategies that rely on being able to buy and sell quickly in several markets at the same time.
Our initial efforts to use cells null for the VDR were hindered by the unexpected inability of these cells to respond to exogenous 1,25(OH)2D3/VDR by regulating endogenous genes.
Her unexpected inability to do so only heightened her sense of loss for the "joys of raising a child without PDD".
Although not unexpected, Rubio's inability to carry his home state served as the final nail in the coffin of a campaign caught perennially on the cusp of breaking through, but falling under the weight of its own expectations.
We considered alternative (potentially trivial) explanations for this unexpected result including an inability to liberate proliferating T cells by mechanical disruption of the lymph nodes selectively at the 72 hr time-point or recruitment of proliferating cells from other sites into the DLN during the 6 hr interval between 72 and 78 hrs.
And today's unexpected story was Woods's inability to take command in his quest to become the first player since Ben Hogan in 1953 to win three consecutive major championships.
This unexpected finding may reflect the inability of our technique to detect localized superoxide release in subcellular microdomains.
Inattentional blindness is the psychological phenomenon of inability to see the unexpected even if it is in plain view.
Inability to cope with unexpected disruption of daily routines, including prolonged house renovations, upset plans for lifestyle change.
However, a sole focus on anticipatory command-and-control management can create brittleness and can lead to the inability to react to unexpected future outcomes (Holling and Meffe 1996).
Indeed, there is much evidence that those who do not grieve end up experiencing breakdowns and the inability to cope at unexpected times.
