OK that’s great, you no longer get white screen when you trigger the cron job manually. Normally the cron job triggers on its own, I only suggested that you trigger it manually to make sure.
You are still experiencing withdrawals which stay in a pending state, even after they are confirmed by an admin AND by the user. And you are using a connection to a full node wallet, which is unlocked. This is very unusual.
First, have you tried entering a new withdrawal again, after upgrading? If your problem was caused by too little memory, then you should repeat the test.
Also, could you please let me know the following?:
1. Which wallet are you using?
2. Normally withdrawals start off with 3 retries. When you trigger the cron job, does the number of remaining retries decrease? Normally when the number gets to 0, you will get an email with an error message.
3. Are there any errors written out into your logs? To enable logging, please see here https://codex.wordpress.org/Debugging_in_WordPress
4. It’s a long shot, but are there any errors in the wallet logs related to your transaction? If, for example, you were using bitcoin core, the logs would be in ~/.bitcoin/debug.log
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