Your license is perpetual, but not free upgrades and support. With macOS "15" SoftRAID 7.6.1 is not going to work. So you can keep using 7.6.1 as long as you stay with Sonoma.

With version 8, we are giving two choices, maintain your annual subscription, with all upgrades included, (or get a 3 years extension with any new enclosure), or go to Standard mode, which will maintain your volume, with no support and limited feature, but free ongoing upgrades.

Software has gotten very expensive to manage and we are trying to accommodate customers.

You are getting hit with the 2019 Mac Pro bug. The volume is not "not mounting", the disks are not showing up is the actual issue.

There is a fair amount of pressure for Apple to fix this.

Licenses for 7 do not "expire", but only have one year (3 with enclosures) upgrades.

Unmounting volumes is a directory issue. Attach a support file.

I would disconnect external drives when upgrading MacOS, personally. I had been bitten a couple times in the past, so never upgrade the OS with drives connected.

Attach a support file, so I can look.

Note: Your license status has zero impact on whether volumes mount, rebuilds happen etc. Your data is not at "risk" because you do not renew.
This is partly why we released 8 the way we did, you can always get a Standard license, which has no major features, but you can see your volume status, and rebuild/replace a disk, but nothing else. So you can feel safe.

I extended your license for a couple months because of the Monitor issue.

If you go to /Library/Application Support/SoftRAID folder, double click on the SoftRAID Monitor, then launch SoftRAID, does that work? (It should)

When you say your volume did not mount, lets be specific, you mean the disks are not appearing in MacOS?

We are having disussions with Apple on this issue. So far, we have determined this affects the Mac Pro 2019 only. It affects multiple vendors and seems to be disk independent. (all brands are affected). Most likely this is an incompatibility introduced between the vendor of the main chip on the card and a bug/change in MacOS, introduced late last year.

We never saw this before, never in Ventura, or in earlier releases of Sonoma.

This is appearing to be a MacOS issue, as it is affecting other cards, Sonnet for example. There are discussions posted on this.

Sonnet posted their bug report number, if you want to post another bug with Apple. If you do, give as much detail as possible. Generally the more user submitted bug reports, the higher priority an issue is. FB13560165

Looks like this has been a minor issue since some time during Ventura, but with 14.4, is now affecting many systems.

I get the point, not trivial.
The SoftRAID Application is "real time". Each disk responds in turn and SoftRAID App updates. If we waited for every disk to respond before posting anything (like Disk Utility, ever notice how slow it is to respond on launch), SoftRAID would appear very slow.

We had anther user with this issue, we can pursue that user, I thought your situation was simpler, as you respond quickly. Don't worry about taking your case apart.