I'm no authority on this but I do have plenty of experience with taking Miracle-Mineral-Supplement in capsules and so I'd like to share some of my own observations with you.
The first thing I'd say is that taking Miracle-Mineral-Supplement in capsule form does bring is own set of challenges. The most obvious being the volatility of the process. IOW. how prone capsule intake is to such things as; throwing-up, upset stomach and diarrhea.
When I started taking capsule, I used to take the 1:5 mixture. However, over time, I found it more convenient to use a 1:1 mixture and so I began taking that instead. However.. as time went one.... I noticed my tolerance for the capsules started to deteriorate and so I adjusted my dosages to try and avoid this. Unfortunately... over time, it got down the the point where I couldn't tolerate even three drops of Miracle-Mineral-Supplement in a capsule, so I eventually gave-up on taking MMS that way entirely.
BTW. on the issue of upset stomach and vomiting, there is good reason to believe that this is the effect of the Chlorous Acid(acidified MMS) on the stomach and not what many people call the "herx" of "die off" effect. Which can be demonstrated by letting the MMS reaction sit on a counter until it expires(aprox. 3 hours) and then placing the solution in a capsule and drinking it. At which point, the solution will be just as volatile as an active one. And though I'm not attacking Jim Humble on this, I think we have very good reason to conclude that he might have been wrong about his original claim on the throwing-up of MMS being a herx reaction. - Or at the very least, not always the case.
Having said that, there are advantages to taking MMS traditionally. And I think your experience outlines this. And that is where the solution is able to come into contact with the mouth, throat and other areas of the digestive tract, whereas the capsules are limited to the stomach and lower digestive tract. And so, in response to your observations, I'd say there is a good possibility that you're experiencing something along these lines insofar as the tongue goes. And so I'd say try going back to the traditional method to see if that helps. And also, I'd try swishing the solution(in your mouth) a few minutes, to see if that doesn't help clear things up.