Please note there are 2 steps needed for saving the layout.
Exit Design mode + Save (as if saving changed data entered).
I assume you did that, but worth clarifying.
There is usually no need to exit the program to use the new layout.
Are you sure you deleted both layout files?
There is one XML file used for saving the matching search items Grid Layout.
The Grid layout file is named “EntitySearch_someEntityScreenName.xml”
The other XML file is used for storing the Entity Editor layout.
The Editor layout file is named “LC_someEntityTypeName.xml”
P.S. the problem reported isn’t related to the Entity type definition in this case but a new bug as confirmed by markjw below. … so you can safely ignore my comments about Entity Type definition below for this problem. Below comment is for a different problem which can cause a conflict with Entity Search layouts:
If you changed Entity Type custom fields after already creating Entities for that type, there can easily be a mismatch between the custom fields schema and the actual entity data.
Do you have lots of customer data already stored? or only developing?
If you already have live data, you can first export the data using Data Export definition in Reports section.I suggest creating a fresh Entity Type and importing the data using Batch Create Entities.
(If the field names changed, you would probably need to edit a copy of your Exported data to match the new field names, or you could create the Data Export to match the new schema appropriately.)