That last link should guide you to the solution; if you tell me what isn’t clear for you there, I’ll gladly help you further.
It’s not related to the capture by the way; it’s your if-statement that checks if the custom object custom.meerwaarde.accounts is different from blank.
This one :
{% ifi custom.meerwaarde.accounts != blank %}
This code :
{% input custom.meerwaarde.accounts as:account_collection range:741 default:741 accounts_var:meerwaarde %}
If you don’t click on the hashtag and select accounts, that object custom.meerwaarde.accounts will stay blank. It’s only when you click on it and select accounts, only then that object will have a value and not be empty. Which you probably didn’t because it showed the desired accounts to begin with.
This is also explained here:
Always be aware when you use default-values (like your default-range).
It’s better to check that’s not empty or blank by default. You could use this for instance:
{% ifi custom.meerwaarde.accounts != blank or meerwaarde.value != 0 %}
The meerwaarde.value will have a value different from zero by default, because there you’ll use the accounts_var which is automatically used to “fill up” a collection of accounts.
Hope this extra info is clear?