How to reproduce:
1. Download attached project (Ensure that CacheServer is enabled in the editor, I have reproduced using Local Mode)
2. Open project, allow the library to build
3. Close Project
4. Open Assets\Editor\EditorPostProcessor.cs, increase m_Version to next number
5. Copy in "FolderToCopyIntoAssets" into Assets directory of the project
6. Reopen project

Actual result: The Editor is failing to check the CacheServer when increasing AssetPostProcessor Version and adding new assets.

Also attached are an example of good and bad behaviour logs, good contains a line like this:
----- Cache Server detail: Total assets requested: 100, Cached Assets: 0, Not available: 100, Not supported: 0.
If the cached assets already exist, then it should read :
----- Cache Server detail: Total assets requested: 100, Cached Assets: 100, Not available: 0, Not supported: 0.
Bad does not produce this line, it does not appear to check the cache server for assets, note that both contain an initial check for a small number of"not supported" assets, I have observed this in customer project also,
To reproduce the "good" log, repeat the steps, but omit step 4.

Reproduced with: 5.6.2p4, 2017.1.3p1, 2017.2.2f1, 2017.3.1p3, 2018.1.0b10, 2018.2.0a3