QGIS » QGIS Application

I just downloaded and installed QGIS a few days ago (version 2.8.2-Wien). I tried pulling in spatial data from sql server (a "geometry" column containing points...used SRID 4326). I click the button that says "Add MSSQL Spatial Layer" and find my points table but when I click the "Add" button it gives me this error (after a minute):
dbname='myDb' host=localhost\\sqlserver2014 srid=4326 type=POINT table="dbo"."Locations_Sample"
(spatial_data_point) sql= is an invalid layer and cannot be loaded. Please check the message log for further info.

The "log message" words in that error were a link in QGIS so I clicked it and it opened a "Log Messages" panel and on that panel (on the "General" tab), it just had the same error message I typed above (with one inconsequential text difference... it says "is an invalid layer - not loaded" instead of "and cannot be loaded").

I tried making that source table ("Locations_Sample") smaller (it was around 120,000 points so I tried making it just 100 points/rows) and that smaller table imported with no problems. I then tried increasing the amount of data in that table and hitting the "Refresh" button in QGIS to find what the row limit was but it succeeded in refreshing every time I tried all the way up to the full 120,000 rows (showing all the points on the map as far as I can tell). This may seem like a workaround but I don't think it really is because every time I close and re-open the project, it errors when trying to load that layer...also other things (like the heatmap raster generator) are failing possibly due to this "invalid layer" issue.

FYI, I subsequently tried loading the table with 100 records at first and then putting all the records in the source table "Locations_Sample" and that always worked (so you don't have to "ramp up" to the full table, you can load it all once it successfully loads the smaller version of that table).

I made sure that all points were between -90 and 90 latitude (not inclusive) and between -180 and 180 longitude (not inclusive). In sql server the STIsValid function indicates that all points are valid ("instance is well-formed, based on its Open Geospatial Consortium (OGC) type"). The following sql returns a count of zero (no invalid points):
SELECT COUNT(*) FROM [dbo].[Locations] WHERE [spatial_data_point].STIsValid()=0