Storage Exceeded Warning
Amazing Fields allows users to dramatically extend the data that can be associated with a board and cards. Unfortunaterly there are limits on this though because there are underlying limits on how much data Trello allows powerups to store on a board or a card. When these limits are hit, Amazing Fields provides a warning and some guidance, but there is nothing the powerup can do to further expand the allowed data. These are hard limits imposed by Trello to protect the boards and cards from having too much data and overwhelming the Trello servers.
There are two places where this will come up.
Board Storage Exceeded
The message above is shown when the configuration being used to setup fields on the board exceeds the space available on the board. This can happen if a huge number of fields are added or if there is a very large amount of configuration of a few fields.
Note that Amazing Fields can handle a large number of fields easily. There are many boards running with nearly 100 fields and it can support even more.
Dropdown Workaround - Card Ref Fields
The most common issue is a drop down field with a huge number of options. For example a parts list or another list where there may be 50+ items with large descriptions for each dropdown item.
A potential workaround for this case is to use the Card Ref field type. I added this field type specifically for the case where you want to have a large number of items selectable in a drop down list and you want to manage that list as a Trello list.
If that doesn't provide the size reduction you need, then I suggest searching through your fields looking for any that may have a more complex setup then others. Usually there are one or two that lead to the problem.
Card Storage Exceeded
This message is shown when the amount of data stored on a single card exceeds the limit Trello can store. This most often occurs when you attempt to put a large amount of text (multiple pages) on a single card.
The only way to work around the issue is to reduce the amount of content you need on the card. One good way to do this is to add a link to a document stored in another system or find another way to simplify the information that is stored on the card.