Laravel Forge Stripe ENV keys stopped working, still working fine on local dev

I have a Laravel 5.5 app using Stripe for subscriptions, deployed on Forge/Digital Ocean.

Everything has been working fine for many months, but today both environmental variables env('PUB_STRIPE_API_KEY') and env('STRIPE_API_KEY') are showing as not present (if(empty) is coming up true for both variables) and Stripe functionality is therefore stopped. Both are present and accounted for in my .ENV file.

STRIPE_API_KEY=sk_test_fPpKzHV49vImGOh4Aqxxxxxx
PUB_STRIPE_API_KEY=pk_test_HrVhWbsRL90qm7RrCbxxxxxx

However, my identical local development instance works just fine. Both were just fine a few days ago and no changes have been made to any Stripe or .ENV code. I'm perplexed.

Other .ENV variables, such as database connection parameters, all seem fine. Only Stripe is effected.

I have checked the .ENV file. I have cleared cache (php artisan cache:clear). No difference. I don't know where to go from here. Any suggestions...?

via Chebli Mohamed