FileVersion.IsCurrentVersion is never true

Hi,
I created a console app to delete old versions (excluding the current version and versions newer than 3 months ago).
The code is:

var file = ctx.Web.GetFileById((Guid)item["UniqueId"]);
ctx.Load(file);
ctx.Load(file.Versions);
ctx.ExecuteQueryRetry();
var lstVersionsToDelete = file.Versions.Where(v => !v.IsCurrentVersion && v.Created <= DateTime.Now.AddMonths(-3)).ToList();
var lstVersion = lstVersionsToDelete.ToList();
foreach (var version in lstVersion)
{
    version.DeleteObject();
}
ctx.ExecuteQueryRetry();

But sometimes I get an error "You cannot delete the current version"!
After investigation it seems the IsCurrentVersion property is never set to true.
Could this be an issue with the framework?
Thanks.

Start with the reported console-app example using FileVersion.IsCurrentVersion, file.Versions, and ExecuteQueryRetry. Reproduce the version-deletion error and inspect whether IsCurrentVersion is populated correctly for the current item in the loaded collection. Done means the current version is reliably identified and the deletion loop no longer attempts to delete it.