I have also checked and I can confirm that the wallet is still holding the bitcoin as at now but OP should be able to use other reliable self custodial wallet to check for confirmation. Since it could be seen through explorer that it is still in the wallet then it means it has not been tampered with so OP can do the needful by making use of another wallet to import his seed phrase and transfer his asset to another wallet before it is too late.

I have had similar experience with one of the popular wallets and it was a terrible one that the wallet could not synchronize showing wallet balance and other statistics details on the app. It still persist after updating the app so I had to user another self custodial wallet to import my seed phrase and it was showing. After confirming it, I quickly transferred my assets to another wallet I created to avoid further issues.