Set static IP in OpenVPN

That's because that is not how you manually assign IP addresses. There is a file ipp.txt that OpenVPN can maintain, so that clients (sometimes) get the same IP address reassigned to them if they reconnect or OpenVPN restarts.

See the sample config:

# Maintain a record of client <-> virtual IP address
# associations in this file.  If OpenVPN goes down or
# is restarted, reconnecting clients can be assigned
# the same virtual IP address from the pool that was
# previously assigned.
ifconfig-pool-persist ipp.txt

But that's not what you've configured.

The files in the ccd directory are interpreted as client-specific configuration. So creating a file ccd/ipp.txt causes OpenVPN to attempt to interpret the file's contents as directives applying to a client named ipp.txt.

This doesn't appear to be what you want.

Let's go back to the sample config:

# To assign specific IP addresses to specific
# clients or if a connecting client has a private
# subnet behind it that should also have VPN access,
# use the subdirectory "ccd" for client-specific
# configuration files (see man page for more info).

# EXAMPLE: Suppose you want to give
# Thelonious a fixed VPN IP address of 10.9.0.1.
# First uncomment out these lines:
;client-config-dir ccd
;route 10.9.0.0 255.255.255.252
# Then add this line to ccd/Thelonious:
#   ifconfig-push 10.9.0.1 10.9.0.2

So it looks like you want a file named ccd/miami-test containing ifconfig-push 10.8.0.5 10.8.0.6.