Fixed: Inbox Filters Stopped After a Handful of Conversations

We fixed an issue that could make filtered views in the Unified Inbox look incomplete.
This was most noticeable with filters such as Last message from them when viewing a single sender. You might see only a few conversations, even though more matching conversations were available.
What was happening
The inbox loads conversations in batches and then applies your filters. If a filtered batch left only a few matching conversations on screen, there was sometimes not enough content to scroll. Since scrolling was what triggered the next batch, the inbox could stop loading too early. This could affect any inbox filter.
What changed
Filtered views now keep loading conversations automatically until the screen is properly filled.
We also made a few related improvements:
- Switching sender, tab, or filter now restarts loading so each new view fills correctly
- Load more conversations appears when a narrow filter reaches the end of what is currently loaded
- Active within now jumps directly to the selected date range instead of working backwards through newer conversations first
- Show archived now works from the Unread tab
- The Campaign filter now lists your campaigns even before their conversations have loaded
Nothing changes about how you use the filters. They simply return more complete results and no longer stop too early.