Did Euclid recorded all mathematical discoveries made in Greece up to his time

No, he didn't.

Explanation:

To put in a little bit of context, Euclid was known for Compiling the works of previous mathematicians and gather it into series of books that he published. With the hope that future generations could get a head start in mathematics without having to redo all the researches from the start.

But, he mentioned that he didn't recorded all mathematical discoveries because of these two reasons:

1. He publicly stated that all discoveries should be proven with scientific methods. This concept hasn't been generally accepted by the people in his time, even among the sciences community. There are several occurrences where theories are written without having sufficient evidence and only rely on deities. He eliminated such theories from his collection.

2. Unlike today, it is extremely hard for mathematicians to gained recognition. There were many brilliant people who made discoveries at that time, but not all of them are recognized by the mass. Making their discoveries left uncovered as they met their death.