Replace a fixed text string (in File Name) with a variable %year%

[ohrenkino]

%year% can be used where you are expected to enter a format string.

@dec

this is one example ...

$replace(%filename%,YEAR UNK,%year%)

If that is the accurate copy then you have replaced the string "YEAR UNK" with the value from YEAR in the user-defined (and probably non-existent) field FILENAME.
if you want to address the filename, use _FILENAME.
Sometimes, as said in

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a screendump helps.

You say that you have used

@dec

both Convert and in Actions

but you do not tell us which Convert function you used and which action.