Need Help! Custom bitly stopped working

[EW]

I don't understand what I'm doing wrong. I am a small business owner (not an enterprise user). I created a bitly, then shortened/customized the "back end."   It used to work, but now it doesn't.  I need help!  This is preventing me from advertising the products I have for sale on Amazon, with a short link.

Here is the full link:  https://www.amazon.com/s/ref=w_bl_sl_s_ap_web_7141123011?ie=UTF8&node=7141123011&field-brandtextbin=Mindful+Tees

Here is the bitly (that used to link directly to the same page above):  http://amzn.to/MindfulTees

Of course I can't edit this now because the customization/source link is permanently connected.

Strangely... I have a second bitly, going to a different Amazon page, that DOES still work - I did not customize the backend of that one.  Here is the working bitly.

https://www.amazon.com/sp?_encoding=UTF8&asin=&isAmazonFulfilled=1&isCBA=&marketplaceID=ATVPDKIKX0DER&orderID=&seller=A25ON275SFW0NQ&tab=&vasStoreID=

http://amzn.to/2jnIpSd

Can you please advise and help?

Thanks.