I created a new vector layer in QGIS, saving as I went along and then I saved the project and logged out. When I went back into the project, I wanted to add some more features to the same layer, so selected the toggle editing icon and highlighted the vector layer. However, not all the options are displaying for me - I can select 'move features' or 'node tool' but can't select the 'add feature' option, for instance.
I took a look at this question which seems to be a similar issue: After re-open of old project file, several layer selections no longer available
As suggested, I tried switching on and off the layers and exiting QGIS again, but so far I can't resolve the issue.
I am relatively new to QGIS.