AWS Lex Bot not recognising intents after inactivity, triggering FallbackIntent

Question

We are experiencing an issue with our AWS Lex bot where everything works fine initially after building it. For example, when we ask, "Are you pet-friendly?", the bot correctly recognizes the PetsIntent and responds appropriately.

However, after a period of inactivity (e.g., over the weekend), when we interact with the bot again, it fails to recognize the same intents and instead triggers the FallbackIntent. After rebuilding the bot, it starts working fine again, but the issue repeats after another period of inactivity.

For instance:

When asking "Are you open now?", the bot should trigger the OpeningHoursIntent, but instead, it triggers the FallbackIntent. Once the bot is rebuilt, it starts recognizing the OpeningHoursIntent correctly. Here’s a sample JSON response from a session when the issue occurred:

{
 "messages": [
  {
   "content": "I'm sorry, I didn't quite catch that.",
   "contentType": "PlainText"
  },
  {
   "content": "Can I help you with anything else?",
   "contentType": "PlainText"
  }
 ],
 "sessionState": {
  "dialogAction": {
   "type": "ElicitIntent"
  },
  "sessionAttributes": {},
  "originatingRequestId": "xxx-xxx"
 },
 "interpretations": [
  {
   "intent": {
    "name": "FallbackIntent",
    "slots": {}
   },
   "interpretationSource": "Lex"
  },
  {
   "nluConfidence": {
    "score": 0.86
   },
   "intent": {
    "name": "OpeningHoursIntent",
    "slots": {}
   },
   "interpretationSource": "Lex"
  },
  {
   "nluConfidence": {
    "score": 0.71
   },
   "intent": {
    "name": "GoodbyeIntent",
    "slots": {}
   },
   "interpretationSource": "Lex"
  },
  {
   "nluConfidence": {
    "score": 0.67
   },
   "intent": {
    "name": "ConfirmationIntent",
    "slots": {}
   },
   "interpretationSource": "Lex"
  },
  {
   "nluConfidence": {
    "score": 0.6
   },
   "intent": {
    "name": "OpenOnChristmasIntent",
    "slots": {}
   },
   "interpretationSource": "Lex"
  }
 ],
 "sessionId": "xxx"
}

Has anyone experienced similar behavior or knows why AWS Lex stops recognizing intents after some time? Any help or suggestions on how to resolve this issue would be appreciated!

Thank you!

I have tried rebuilding the Lex bot, which temporarily solves the issue, and the bot starts recognizing intents correctly again. However, after a period of inactivity (e.g., over a weekend), the problem returns, and the bot triggers the FallbackIntent instead of the correct intents.