First, try rebuilding your permalinks. Go to Settings >> Permalinks and click Save, which will rebuild them. If that doesn’t work, go into your Settings >> Reading >> Blog pages show at most setting and try increasing or decreasing that and see how that changes things.
Some themes have a setting that lets you adjust how many posts per page display in the loop that can conflict with the main WordPress setting, so if you can edit your theme options, try ensuring there isn’t a setting in there you need to adjust.
One thing I’d also try if none of this works is disabling all of your plugins temporarily and reverting to the default WordPress theme just to isolate the cause of the issue. If it works, then switch back to your current theme. If it still works, you’ll know it’s plugin-related. If not, you’ll know it’s theme-related.