Primer is thick and uneven
If the primer or walls were outside the temperature range specified on the primer can, it's hard to demand the primer to perform to spec, and any number of poor results should be expected.
Despite having mixed &quot;as much as we could&quot; if it was still cold, it's highly likely that it wasn't mixed properly. Therefore, what went on the wall wasn't the prescribed mixture of solid &amp; liquid, and, therefore, what's left in the can isn't the proper mixture, either.
It's likely that what's left in the can will no longer perform as expected. Once warmed back to the manufacturer specified temperature range, there's a good chance you'll get a smooth coat if you choose to apply what's left, but it's likely not to cover as you'd like it to.
I'd suggest that this can is now likely a good learning experience.

Cold temperatures will not, in my experience, permanently harm paint. We have what could generously be described as a &quot;three season porch&quot; on our house. It was, for many years, uninsulated and unheated. We use it to store paint, among other things, and the temperature back there has probably dropped below freezing, if not below 0°F more than once, yet paint stored there, once warmed to room temperature, has been applied successfully. It may not have been a &quot;perfect&quot; coat, but it was quite presentable.