Here is my project file folder zipped up on Google Drive that I'm sharing (it's about 537MB).
The project can be opened, shows the name on the header, but no data grid ever appears. I do not see anything abnormal in the terminal or in the browser console. Project saving had already been done and seemed to be automatically performed again when I startup OpenRefine freshly, or shut down with CTRL-C in terminal, and open the project, wait for it to show the data grid, but it never does (even with 24G given to OpenRefine, or even 64G), there's something mysterious happening and it's not bubbling up to any user facing surface I can see. Not the OpenRefine server output, or the browser's console. So wondering what happens if others try? I could not export of course directly because of the problem, so you'll need to copy it to your OpenRefine working directory I guess, and then extract it, and startup OpenRefine which hopefully sees the project and updates the workspace and workspace.old as it should?
If I attempt to open the NPM-Packages project from the Project listing with 4.0 latest build... I get the following:
10:43:47.670 [ refine] 200 POST /command/core/load-language [8ms] (13ms)
10:43:47.695 [ refine] 200 GET /command/core/get-all-preferences [4ms] (25ms)
java.io.FileNotFoundException: C:\Users\thadg\AppData\Roaming\OpenRefine4\2517830429055.project\history.json (The system cannot find the file specified)
at java.base/java.io.FileInputStream.open0(Native Method)
at java.base/java.io.FileInputStream.open(FileInputStream.java:213)
at java.base/java.io.FileInputStream.<init>(FileInputStream.java:152)
at com.fasterxml.jackson.core.JsonFactory.createParser(JsonFactory.java:1029)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3413)
at org.openrefine.history.HistoryEntryManager.load(HistoryEntryManager.java:102)
at org.openrefine.io.FileProjectManager.loadProject(FileProjectManager.java:291)
at org.openrefine.ProjectManager.getProject(ProjectManager.java:490)