Page Header dialog greying out

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RapidWeaver Version: 6.3.1 (15010)
System Version: 10.10.5
Hardware: 27-Inch iMac , 8GB Memory.

Sometimes when I paste header code into the appropriate tab on a page, the dialog greys out. If I save, shutdown RW, then re-open, the the header code displays as it should. So the code is going in there just fine, it just seems that it requires a re-start in order to display the code properly under the header tab (page info).

Expected Result:
The code pasted into the Header tab should just display as required once pasted.

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