I also can send texts but not receive them. I had installed Textra because I thought it would not have this same problem that I am having with the Samsung installed messaging app on my Galaxy S7 which started two days also. I have Google Voice on my phone in order to get transcripts of voice mails since I am deaf. But now Google Voice is receiving all my texts, even though I set it not to and even though I set Textra as the default messaging app. I even followed your advice to uncheck the battery optimizer for Textra but that did not help either. Uninstalling Google Voice did not fix the problem, neither for the Samsung messaging app nor for Textra. Any suggestions?

The icon appears, showing I have a text. I don't receive any text and the number increases from the same recipient. I have uninstalled and reinstalled, did not fix issue.