diff --git a/rslib/src/scheduler/fsrs/memory_state.rs b/rslib/src/scheduler/fsrs/memory_state.rs
index f7021beab..1868525a7 100644
--- a/rslib/src/scheduler/fsrs/memory_state.rs
+++ b/rslib/src/scheduler/fsrs/memory_state.rs
@@ -85,8 +85,8 @@ impl Collection {
                 progress.update(true, |state| state.current_cards = idx as u32 + 1)?;
                 let mut card = self.storage.get_card(card_id)?.or_not_found(card_id)?;
                 let original = card.clone();
-                if let Some(req) = &req {
-                    card.set_memory_state(&fsrs, item, historical_retention.unwrap())?;
+                if let (Some(req), Some(item)) = (&req, item) {
+                    card.set_memory_state(&fsrs, Some(item), historical_retention.unwrap())?;
                     card.desired_retention = desired_retention;
                     // if rescheduling
                     if let Some(reviews) = &last_revlog_info {
@@ -163,11 +163,20 @@ impl Collection {
             historical_retention,
             ignore_revlogs_before_ms_from_config(&config)?,
         )?;
-        card.set_memory_state(&fsrs, item, historical_retention)?;
-        Ok(ComputeMemoryStateResponse {
-            state: card.memory_state.map(Into::into),
-            desired_retention,
-        })
+        if item.is_some() {
+            card.set_memory_state(&fsrs, item, historical_retention)?;
+            Ok(ComputeMemoryStateResponse {
+                state: card.memory_state.map(Into::into),
+                desired_retention,
+            })
+        } else {
+            card.memory_state = None;
+            card.desired_retention = None;
+            Ok(ComputeMemoryStateResponse {
+                state: None,
+                desired_retention,
+            })
+        }
     }
 }
 
diff --git a/rslib/src/scheduler/fsrs/params.rs b/rslib/src/scheduler/fsrs/params.rs
index a5b916746..84fbed48b 100644
--- a/rslib/src/scheduler/fsrs/params.rs
+++ b/rslib/src/scheduler/fsrs/params.rs
@@ -340,6 +340,9 @@ pub(crate) fn reviews_for_fsrs(
         if idx > 0 {
             entries.drain(..idx);
         }
+    } else {
+        // if no valid user grades were found, ignore the card.
+        return None;
     }
 
     // Filter out unwanted entries
@@ -424,7 +427,7 @@ fn revlog_entry_to_proto(e: RevlogEntry) -> anki_proto::stats::RevlogEntry {
 pub(crate) mod tests {
     use super::*;
 
-    const NEXT_DAY_AT: TimestampSecs = TimestampSecs(86400 * 100);
+    const NEXT_DAY_AT: TimestampSecs = TimestampSecs(86400 * 1000);
 
     fn days_ago_ms(days_ago: i64) -> TimestampMillis {
         ((NEXT_DAY_AT.0 - days_ago * 86400) * 1000).into()
@@ -709,4 +712,14 @@ pub(crate) mod tests {
             2
         );
     }
+
+    #[test]
+    fn ignore_before_after_last_revlog_entry() {
+        let revlogs = &[
+            revlog(RevlogReviewKind::Learning, 10),
+            revlog(RevlogReviewKind::Review, 6),
+        ];
+        // L R |
+        assert_eq!(convert_ignore_before(revlogs, false, days_ago_ms(4)), None);
+    }
 }