The BINs that are available for card issuance are cycled by issuing banks over time. If a card BIN goes out of rotation, new cards cannot be issued using that BIN until it becomes available again. Note that cards issued on those BINs will still function normally.
You can check which BINs are currently available for issuance using our card BIN endpoint: https://docs.thepennyinc.com/reference/listbins
Another thing to note is that if you are using the target_merchant_identifier when issuing, you should not specify a card BIN as this will override the dynamic BIN selection system.