Tapestri Designer uses VarSome to resolve HGVS targets. A target can be resolved to multiple regions as explained in this FAQ. Amplicons are designed based on these submitted regions. If a target is resolved to multiple regions that are not close, then separate amplicons are designed to cover each of the regions.
A panel typically contains multiple targets resulting in multiple regions. When Designer creates the amplicons, it tries to cover as many targets as possible. Designer selects the minimum number of amplicons with maximum coverage. In the process, it is possible that all the regions for a single target are not covered. To avoid this, we add the transcript ID to the target that provides specificity to Designer so that it would then design only for a single region, thereby increasing coverage for it.