NAB rejection

Applied to NAB for a loan after settlement of mortgage (not with NAB). Intent was to roll a MyCard over, but NAB declined - after hitting my credit report. Income/expenses and leverage shouldn't be an issue, but clearly something must have hit a threshold for NAB.

Not wedded to NAB, but curious how long others would wait until they applied to the next bank? I'm surprised this was an issue because my income has gone up materially, and I've reduced my total debt over the last 12 months.

Also do you declare the limit of the card you are planning to close - I've previously had people tell me not to, but that seems inaccurate? I currently carry a balance, so was going to use an 0% balance transfer offer and can't easily pay out and close before applying...