Of course, without seeing the macro or knowing the app(s) involved or being told the context or having a description of what should but isn't happening -- there's no point in saying more.
Try adding a pause after the pasteāthat can take a bit of time, especially if it's a reasonably-sized block of text.
You might want to even try putting a general delay between all the actions, which you can do by putting a Set Action Delay action as the first action in the macro:
You could then easily play around with the delay. This will, of course, slow down the entire macro, but sometimes you need delays between keystroke actions, and this is a good way to test doing so between every action, instead of trying to insert them in multiple spots, etc.
As @griffman points out, you may want to change the āX for KM's "Cut" Action, which pauses execution until the Clipboard changes (which means the Cut has happened), and add a short "Pause" after the āV -- I only tested with short, unformatted, paragraphs.
The action, presuming they run, will definitely be simulating the keystrokes.
The simulated keystrokes go in to the system event queue, and eventually are read out of the queue and processed.
Typically when keys ādo nothingā, it is because the application is not ready for them, or the system/application handles them and then messes up because it is still doing something else.
If you are changing text focus, then you need to ensure that that change has fully happened before the keys are sent into the event queue. Otherwise the keys may come out in the old focus before the change happens. For example, creating a window frequently takes time, and the simulated events might easily be lost if they are sent while the application is still creating the window.
Another common case is web forms, where the form JavaScript frequently notices a change, reads the field, validates the field, and then writes it back. If, while it is doing this, another key is simulated, that second key could go in to the field and then promptly be overwritten by the JavaScript, resulting it characters appearing to be lost.
Slowing down the typing or actions, or adding Pauses can typically resolve such issues.