Google Analytics can have a data processing latency of up to 48 hours. Sometimes even 72 hours for goals and transaction data. This is normal behaviour for Google Analytics and is noted in the Google Analytics Help Center documentation.
Other things to keep in mind:
- Visitors can opt out of analytics tracking.
- If a page takes too long to load, or a visitor uses the browser stop or back button, or navigates to a different page quickly, their pageview may not be tracked by analytics.
GA wasn't designed to track all visitor traffic, it was designed to look at trends over time.
GA reports reflect only a part of your real statistics.
Please note: Its highly recommended to install the Google Analytics code in your header of your website, before the </head> tag. Will help Google Analytics to track more visitors.