The block-edit page does not correctly select the clicked block; rather, it retrieves all blocks (the query in the network inspector is simply .../manualblocks; there is no ?query clause whatsoever.
- create a block for any user. Enter "AAA" in the "Block description"
- create a second block for the same user. Enter "BBB" in the "Block description"
- click the "BBB" row to edit it
- edit-block pane contains the "BBB" details
- You should be able to close the edit pane with the X in the upper left
- edit-block pane contains the "AAA" details OR details that pertain to neither (maybe it's showing the patron block from a totally different user?)
- You can't close the edit pane with the X in the upper left
- create a block for user-a with "AAA" in the description
- create a block for user-b with "BBB" in the description
- edit block for user-b; it will contain "AAA"