This quick tutorial will cover how to clear your SPD 2013 Cache, which comes in handy especially when working with SPD 2010 & SPD 2013. Clearing the cache will remove any of your past connection history as well give you a "clean slate" to work from. The cache is not even cleared after doing a reinstall, so this really is the only way to clear it.
Versioning with check-in/out are great but not always preferred, and certainly not infallible. As I learned on a project a few years ago - and recently bit me again when my new machine was not similarly configured - SharePoint Designer has a dirty little habit of caching files, including say the XML/XSLT, JS and CSS you might be working with on your site.
No need to fret though; buried in the settings of each version is a toggle that will ensure SPD never sets you back by loading a cached file
1. Close SPD if it is open
2. Open My Computer
a. Click the address bar
3. Paste %USERPROFILE%\AppData\Local\Microsoft\WebsiteCache
4. Delete everything within this location
5. Click the address bar
6. Paste %APPDATA%\Microsoft\Web Server Extensions\Cache
7. Delete everything in this location
SharePoint Designer 2010 and 2013
1. Navigate to File menu -> Options -> General -> Application Options
2. On the "General" tab, under the "General" heading, uncheck "Cache site data across SharePoint Designer sessions"
This is a quick couple of steps in order to clear your cache and to hopefully resolve SharePoint Designer anomalies which present themselves from time to time