[Tooltip, ContextMenu] FXML defined id is null

I defined and used a tooltip in a FXML file as follows and when I check the tooltip in runtime, the tooltip is there but the id is missing!

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  <fx:define>
<Tooltip fx:id="providerNumberTooltip_TT" text="Provider Number33"/>
</fx:define>
    <Label text="Provider Number:" fx:id="providerNumber_c_LB" tooltip="$providerNumberTooltip_TT"/>
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control.getTooltip().getText() -> "Provider Number33"

control.getTooltip().getId() -> null