I think I have a problem in understanding how the ‘Identify Features’ tool works in QGIS with a shapefile that might have some kind of error. I don’t know quite enough QGIS to be sure I’m asking this question the right way, so please bear with me while I try my best. The Shapefile I’m using can be downloaded from here: https://gis-countyofdane.opendata.arcgis.com/datasets/supervisor-districts-1/explore (and mirrored here: http://pages.cs.wisc.edu/~epaulson/Supervisor_Districts.zip )
I have a shapefile of 37 County Supervisor districts. I am using QGIS 3.20 on a Mac, and QGIS displays them just fine, but for a handful of them, I can’t select them using the ‘Identify Features’ tool - if I click on one of these problematic districts QGIS says ‘No features found at this position’. I can select any of those features by going to the Attribute Table for the layer and clicking on the row for any of the 37 districts. (The attached screenshot is when I tried to click on the most southwest district)
My first idea was to try and check for invalid geometry, so I used the ‘Check validity’ tool with the ‘GEOS’ option, and it identifies 5 districts/features that have problems and lists them in the ‘Invalid output’ layer, all on the eastern side of the county. However, one of the five features was one that I could click on with ‘Identify Features’ in the original data (DistrictNu 20, the district that is the northeast corner) and one of those features that I cannot click on with the ‘Identify features’ in the original layer is listed in the ‘Valid Output’ layer (DistrictNu 30, the district that is the southwest corner). So I’m not sure if there’s something going on with valid geometry or not.
As a further test, I used the ‘Fix geometries’ tool, and that seemingly works for nearly everything - in the resulting ‘Fixed Geometries’ layer, I can now click on all of the features on the east side of the county with the ‘Identify Features’ tool, including the 4 that I couldn’t before as well as the 1 that I could click on in the original data but was included in the ‘Invalid Output’ layer from ‘Check Validity’. But now, DistrictNu 30 in the southwest corner is not drawn at all in the ‘Fixed Geometries’ layer. (It is included in the Attribute Table for the layer, I see all 37 districts in the table, but I only see 36 drawn, even if I zoom very far out so there’s no issue in anything being partially clipped)
I’m at a loss to understand what problems this shapefile might have, so I’m not sure where to dig next. I’d like to be able to click on any of the 37 districts with the ‘Identify Features’ tool, but I don’t know how to modify/repair this shapefile so that I can. The other approaches that I’ve seen on blogposts and tutorial videos - using ‘Check Validity’ tool to find errors that I could manually correct, or the ‘Fix geometries’ tool to automatically repair any errors, don’t seem to get me to a shapefile where I can click on each of the 37 districts. Is there another tool in QGIS I should use, or is there something deeper wrong with the shapefile I’m trying to explore?