title: EFCORE 2.2.6 Simple join throws Must be a reducible node
body: <p>I'm upgrading an application to EF 2.2, but using EFCore 2.2.6 keeps throwing "Must be a reducible node" ArgumentException when I try to do a simple join.</p>
  
  <p>like</p>
  
  <pre><code>var list = (from a in db.TableA().Include("TableC")
         join b in inMemoryList on a.Id equals b.AId
         select a).ToList();
  </code></pre>
  
  <p>If I change to</p>
  
  <pre><code>var list = (from a in db.TableA().ToList()
         join b in inMemoryList on a.Id equals b.AId
         select a).ToList();
  </code></pre>
  
  <p>It works, but slow down the process. </p>
  
  <p>Any ideas ? Thanks</p>