A counterexample to ought implies can
Here is a standard way of interpreting the doctrine that ought implies can:
If you ought to perform action A at time T, then it must be the case that you can perform action A at time T.
Alexandra King proposes counterexamples to this principle where the action you ought to perform involves having certain mental states. Suppose you ought to apologize at a certain time. But apologizing involves more than just saying sorry. It involves expressing certain emotions in saying this and therefore having these emotions. But emotions are not something that are under immediate control, such that one can have the emotion at a given time just by willing to have it. Thus it may be that a person ought to apologize at a given time, or at some point within a given period of time, but cannot apologize at that time, because they do not have the appropriate emotions. King gives the example of parents rightly telling their child to apologize to Grandma.
King, A. 2014. Actions That We Ought, But Canít. Ratio 27: 316-327.