JVM Arguments get lost after re-enabling them

When you put in a value like '-Xmx4G' into the JVM Arguments and then disable it(for whatever reason) and re-enable it it will be set to the default 1G instead of what I put in earlier.

What I expected to happen was...:
It should kept the JVM Arguments to the value that I put in before disabling it.

What actually happened was...:
It reset the JVM Arguments to -Xmx1G

Steps to Reproduce:
1.Change the JVM Argument
2. Disable the JVM Argument
3. Enable it
4. It has been reset to the default argument