The developers of the plugin we use for ElfBuckz have responded to me on the issue of occasional topups failing. Apparently the fault lay with the PayPal payments plugin, which broke some Woocommerce automations. This is supposedly now fixed, but if you do notice your top-ups failing again, let me know!
Update on Subscriptions stuck on hold
With the help of another affected user, I got to the bottom of why we were seeing some subscriptions paused, or stuck "on hold" even after successfully renewing them, and it's not what you'd think..
Woocommerce emits orders for every change to your subscription, based on a "subscription" ID (low numbers), and ever increasing order IDs (high numbers). Users can have multiple subscriptions, so as a result, we "summarize" all your services by combining a collection of files which look like this:
In the case of the example above, if order 123 had been an "on hold" order, it would have overwritten any changes applied in order 10945 (the files are mergd downwards).
This curly little bug is now to bed , and subscriptions and renewals should be more stable now!